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TEXT  BOOK 


OF 

atural  History. 


by  ADRIAN  J.  EBELL,  Bli.B.,  M.D. 


PART  x. 


ENDING  TO  THE  STRUCTURAL  FEATURES  OF  CLASSES  IN  TH 
ANIMAL  KINGDOM. 


ebell  &  CO  . 

Publishers  of  School  and  Popular  Scientific  Works, 
Room  18,  Cooper  Union  Building, 

NEW  YORK. 


Entered  according  to  Act  of  Congress  in  the  year  1870,  by  Adrian  J  Isbell, 
in  the  Office  of  the  Librarian  of  Congress,  at  Washington. 


Stereotyped  and  printed  by 
^olhemus  <Sc  Pearson,  139  Pulton  St.,  N.  V. 


*=? 


590 

Fir3t 


I 

J 


PREFACE. 


ThIe  following  pages  were  published  by  the  author  for 
se  i.|n  the  classes  and  schools  to  which  he  lectures  on 
Natu  ral  History.  Meeting  that  end,  they  will  have  an- 
weredi  the  special  purpose  for  which  they  were  prepared. 
If,  hoyvever,  the  plan  he  has  adopted  for  his  own  system 
of  ins /truction,  may  chance  to  please  his  co-laborers  in  the 
work,  \  it  will  rejoice  him  to  share  with  them  in  its  results. 

He  would  beg,  in  this  connection,  the  privilege  of  ex¬ 
pressing  his  most  heartfelt  thanks  to  his  many  patrons — 
j  principals  of  schools  and  seminaries  in  all  parts  of  the 
land  ,  especially  in  the  cities  of  Philadelphia,  New  York, 
Balt  imore  and  Troy — for  the  kind  support  and  counten- 
^Incetf  with  which  they  have  encouraged  his  labors  for  the 
past J  five  years  ;  for  if  any  merit  exist  in  this  effort,  it  is 
^_,the  Jresult  of  their  fostering,  and  has  been  drawn  forth  by 
— them  words  of  encouragement  and  approval. 

3  f 

^  In  this  number  the  department  of  Zoology  has  been  con- 
-sideried  only  as  far  as  the  Classes,  but  it  is  hoped  that  by 
‘^th  ' 


/jjf‘  Tc 
pres 


CM 


G) 

CM 


summer  of  ’71  the  major  part,  if  not  the  whole,  of  the 
xt  Books  of  Natural  History”  may  be  ready  for  the 
s. 


N]  £w  York,  December  1st,  1870. 


CONTENTS 


w 


ChaiK 


3?  AH,  T  I. 


Page 


Preface  .  4 

Introduction — General  Review  of  Natural  Science  5 

Plan  of  N  atural  History . 8 

Organic  and  Inorganic  Matter . 12 

Divisions  of  Inorganic  Matter . 16 

Divisions  of  Organic  Matter . 18 

Methods  of  Study — Zoology . 22 

Generation — Methods  and  Organs  of . 25 

Digestion . 28 

Respiration . 30 

Organs  of  Respiration . 32 

Circulation . 33 

Sensation  and  Nervous  Systems  ...  ...  35 

The  Five  Senses  . 37 

Motion . 40 

Systems  of  Classification . 41 

Methods  of  Study — Classification  and  Natural  His¬ 
tory  . 43 


11 


CONTENTS. 


Chap. 

XVII. 

XVIII. 

XIX. 

XX. 

XXI. 


XXII. 

XXIII. 

XXIV. 

XXV. 

XXVI. 

XXVII. 

XXVIII. 

XXIX 

XXX. 


XXXI. 


Page 

46 


OH* 

v 


Type  of  Protozoa . 

Protozoa — Nervous  System  and  Organs 

Sense . 

Protozoa — Natural  History . 

Type  of  Kadiates . 

Radiates — Nervous  System  and  Organs  dk£ 

Sense . 

Type  of  Mollusks . 

Mollusks — Respiration  and  Circulation — Nei,_ 

vo us  System . 

Mollusks — Integument  or  Shell  of  ...  . 

Articulates — Arrangement  of  Rings  .  .  . 

Articulates — Nutritive  Organs . 

Articulates — The  Nervous  System — Organs  of 

Sense  and  Natural  History . 

T)pe  of  Vertebrates . 

Vertebrates — Circulation . 

Vertebrates  —  Nervous  System  —  Organs  of 

Sense  . 

Vertebrates — Organs  of  Motion — Bony  System 
— Engravings  of  Typical  Vertebrse  and 
Skeleton . $7 


49 

51 

53 

56 

59 

61 

64 

68 

70 

72 

76 

79 

82 


92 

95 


XXXII.  Vertebrates — Muscular  System 
XXXIII.  Table  of  Classes  ... 


TEXT  BOOK 


OF 


NATURAL  HISTORY. 


CHAPTEE  I. 


INTRODUCTION. 


Natural  History,  in  the  wider  meaning  of  the  term, 
teats  of  the  appearances  and  connections  of  nature  as  a 
whole,  or  of  its  several  departments  by  themselves.  It  is 
us  Tally,  however,  understood  to  mean  the  study  of  plants 
and  animals. 

Before  we  enter  into  the  specific  study  of  the  animal 
ki  lgdom,  we  shall  review  its  relations  with  the  other  de- 
pi  rtments  of  nature. 

The  book  shall  be  divided  into  three  parts  :  1st.  The 
0  Ejects  ;  2nd.  The  Plan  ;  and  3rd.  The  Methods  of 
Si  tdy  of  Natural  History. 

The  first  of  these,  though  of  most  importance,  will  oc- 

*py  much  the  least  space  and  time  in  consideration, 


6 


INTRODUCTION. 


1st. — Objects  oe  Study. 

The  chief  objects  to  be  sought  after  in  the  study  of 
nature,  especially  in  the  first  general  perusal  of  the  sub-  £ 
ject,  are  two :  First,  The  Development  of  our  observing 
powers  /  end  Second,  An  acquaintance  with  the  prime  \ 
laws  and  divisions  of  Nature.  Besides  these,  are  all  the 
more  special  aims  and  ends  of  subsequent  study ;  but  our 
attention  in  this  work  shall  be  confined  to  the  furthering, 
chiefly,  if  not  alone,  of  the  ends  mentioned. 

The  observing  powers ,  through  the  medium  of  the  five 
senses,  are  the  first  faculties  put  forth  in  the  development 
of  the  mind,  the  first  educators  of  our  reflective  faculties, 
and  the  only  methods  we  have  of  gathering  facts  of  na¬ 
ture  from  which  to  educe  the  laws  and  principles  of 
science. 

A.  —  The  training  of  the  observing  powers  is  attained 
only  by  means  of  thinking  as  we  perceive. 

The  various  objects  in  nature  and  art  may  present  them¬ 
selves  to  our  senses  without  producing  any  greater  effect 
in  our  mind,  or  on  our  powers  of  observation,  than  they 
do  upon  the  horse  or  ox,  until  we  learn  by  thought  to 
group  and  associate  them  in  their  various  divisions. 

This  is  the  chief  advantage  to  be  gained  by  fixing!  in 
our  minds  the  general  tables  and  outlines  of  Nature  mat 
will  be  given  throughout  this  work  ;  and  it  cannot  be  too 
urgently  pressed  upon  the  learner,  that  the  first  tallies 
(I,  II,  Y,  VI)  be  clearly  memorized. 

B.  — The  prime  laws  of  nature  are  the  methods  of  ac-  ^ 
tion  of  forces  around  us,  and  the  relations  of  objects  to 

J 

4 


INTRODUCTION. 


7 


each  other.  While  a  complete  acquaintance  with  these 
would  require  a  review  of  all  departments  of  Nature,  we 
have,  as  it  were,  a  compendium  of  all  departments  in  the 
Structure  and  Life  of  the  Animal  Kingdom . 

Therefore  Zoology,  treating  (1st)  of  the  structure  and 
life ,  (2nd)  the  classification ,  and  (3rd)  the  distribution , 
relations  and  uses  of  the  animal  kingdom ,  is  the  depart¬ 
ment  of  Natural  Science  chosen,  in  preference  to  any 
other,  to  be  the  channel  through  which  to  attain  these  two 
chief  ends. 


8 


PLAN  OP  NATURAL  HISTORY. 


CHAPTER  II. 

PLAN  OF  NATURAL  HISTORY. 

• 

The  plan  or  arrangement  of  Natural  History  comprises 
a  review  of  the  relations  and  connections  of  the  different 
departments  of  nature  considered  as  a  unit. 

Nature  in  its  great  variety  of  forms  and  appearances,  is 
most  intimately  connected  throughout ;  and  the  different 
sciences  and  departments  of  human  knowledge  are  but  so 
many  points  of  sight  of  a  single  creation. 

This  unity  in  nature  extends,  not  merely  to  its  different 
departments  on  this  earth,  but,  as  far  as  our  observations 
have  been  able  to  reach,  throughout  the  infinity  of  space. 
The  laws  of  physical,  and  even  of  chemical  science,  as 
lately  revealed  by  the  spectroscope,  are  the  same  in  bodies 
remote  in  space  as  on  our  planet. 

Reasoning  from  analogy,  we  might  bespeak  a  similarity 
also  for  the  laws  of  vital  force.  We  propose  in  this  con¬ 
nection  to  give  merely  an  outline  of  this  plan  ;  comme  nc¬ 
ing  with  nature  as  a  unit,  and  tracing  out  its  prime ,  or 
chief  divisions. 

Although,  an  infinite  variety  of  forms  and  appearances 
surround  us,  and  nature  seems  inexhaustible  in  her  shapes 
and  phenomena,  yet  all  may  be  so  classified,  that  we  dan 
review  the  whole  in  its  larger  divisions  and  groups,  ass  a 
single  creation:  hence  before  we  commence  the  study  of 
any  special  department  we  shall  review  the  comprehens  ive 
plan  of  the  field,  first  in  the  following  table,  and  aft*er- 

0 


PLAN  OF  NATURAL  HISTORY. 


9 


: 


wards  in  the  chief  points  of  relation  and  difference  be¬ 
tween  its  several  parts;  that  we  may  entertain  a  clear  con¬ 
ception  of  the  whole  of  nature  as  a  unit,  designed  and 
created  by  a  single  God. 

All  that  our  senses  can  perceive  of  nature  may  be  sepa¬ 
rated  into  the  two  divisions  of  Matter  and  Force,  wholly 
different  in  their  character,  though  inseparable  in  their 
existence. 

Each  of  these  are  still  further  distinguished  by  their 
kind  or  character,  viz.,  Force,  into  physical,  chemical,  and 
vital ;  and  Matter,  into  organic  and  inorganic. 


Table  I. 


Nature 


Force  .  . 


f  Physical, 

i 

<(  Chemical, 

L  Vital. 
Organic  . 


(  Plants, 

^  Animals. 


Matter 


< 


Inorganic  . 


'Elements, 

Metals, 

Minerals, 

Pocks. 


We  do  not  propose  here  to  enter  into  any  abstract 
metaphysical  discussion  about  the  difference  between 
Matter  and  Force. 


Whatever  occupies  space,  and  is  tangible  to  our  senses, 
we  call  Matter;  and  any  agent  or  power  that  is  capable 
of  changing  the  condition  of,  or  moving  matter — Force. 
We  know  this  definition  is  incomplete,  but  if  any  one 
will  present  a  better,  we  shall  gladly  accept  it. 


10 


PLAN  OF  NATURAL  HISTORY. 


It  is  not  within  the  province  of  Natural  Science,  nor 
indeed,  within  the  capability  of  man,  to  answer  the 
What  and  Why ,  in  relation  to  the  character  and  appear¬ 
ances  of  Matter  and  Force.  They  are  the  embodiment, 
or  expression  of  an  Infinite  Creative  Mind,  beyond  the 
reach  of  human  intellect ;  and  so  are  themselves  incom¬ 
prehensible.  We  would  request  any  one  who  questions 
this  to  give  us  an  exhaustive  definition  of  physical, 
chemical  or  vital  force,  or  any  one  of  their  various 
evincements,  as  gravitation,  electricity,  magnetism,  or 
of  any  particle  of  organic  or  inorganic  matter,  beyond 
a  description  of  their  appearances  to  our  senses. 

It  is  of  these  appearances  to  our  senses  of  Matter 
arid  Force  alone  that  we  can  speak. 

The  entire  field  of  Natural  Science ,  then,  contracts 
itself  into  an  observance  of  the  appearances  of  Matter 
and  Force,  and  of  their  various  relations  ;  or,  in  other 
words,  of  the  how  objects  and  forces  appear  to  our 
senses  and  influence  each  other.  The  reasonings  and 
theories,  which  are  not  directly  supported  by  observation, 
belong  to  the  metaphysical  and  speculative  sciences. 

Physical  Force  evinces  itself  at  all  times  from  objects 
that  are  alone,  and  unassociated  with  others,  as  well  as 
in  their  combined  conditions,  £//.,  a  piece  of  wood 
or  stone  ever  evinces  the  power  of  gravitation,  cohesion, 
etc.,  while  they  have  to  be  brought  into  favorable  rela¬ 
tions  and  under  favorable  circumstances,  to  show  forth 
the  chemical  forces  they  are  capable  of,  ey.,  an  acid  and 
a  base  or  alkali  have  an  affinity  for  each  other,  but  will 
not  evince  it,  except  under  the  condition  of  solutions. 

Physical  and  chemical  forces  may  be,  and  doubtless  are, 
correllated  forms  of  each  other  ;  but  Vital  force  is  not  as 


PLAN  OF  NATURAL  HISTORY. 


11 


easily  disposed  of  in  that  way  ;  else,  we  might  produce 
organic  forms  in  our  laboratories.  Vital  Force  is  the 
power  that  produces  and  constitutes  what  we  call  the 
life  or  living  force  of  plants  and  animals,  and  by  no 
means  merely  another  form  of  electricity  or  magnetism. 
Names  that  of  late  have  been  made  the  scape-goats  of 
all  our  ignorance  and  every  power  or  force  that  has 
been  thought  inexplicable  (though  indeed  no  one  is  more 
so  than  another),  has  been  called  electrical  or  magnetic. 

In  review,  we  might,  then,  distinguish  these  three 
forces  by  their  different  conditions  of  action,  thus — 

Physical  Force ,  existing  in  all  nature  and  through¬ 
out  all  space,  evincing  itself  from  all  objects,  at  all 
times,  and  under  all  conditions,  as  gravitation,  electri¬ 
city,  magnetism,  cohesion,  repulsion,  etc. 

Chemical  Force ,  requiring  for  its  evincement  a  cer¬ 
tain  favorable  relation  of  objects  called  chemical  affin¬ 
ity,  and  certain  circumstances  or  conditions,  as  heat  or 
moisture,  under  wdiich  alone  the  force  will  show  itself, 
or  act,  eg ,  salt  and  sand  have  no  chemical  affinity 
and  will  not  set  up  chemical  action  under  any  circum¬ 
stance,  but  tartaric  acid  and  soda  have ;  yet,  brought 
together  dry,  will  not  affect  each  other  ;  if  moistened, 
however,  tiny  at  once  set  up  chemical  action.  So,  also, 
there  is  a  chemical  affinity  between  the  organic  struc¬ 
ture  of  a  piece  of  wood  and  the  oxygen  of  the  air, 
but  a  certain  degree  of  heat  is  necessary  to  commence 
this  action,  and  then  we  say  the  wood  burns. 

Regarding  Vital  Force,  we  can  merely  say  that  it  is 
the  living  force  of  the  plant,  or  the  animal  /  always 
associating  with  itself,  in  its  action,  both  physical  and 
chemical  force,  but  itself  different  from  either. 


12 


ORGANIC  AND  INORGANIC  MATTER. 


CHAPTEE  III. 

ORGANIC  AND  INORGANIC  MATTER. 

Matter,  we  found,  divided  into  the  two  great  divisions, 
Organic  and  Inorganic  ;  differing  from  each  other  chiefly 
in  four  respects : 

1st.  Structure. 

2d.  Origin. 

3d.  Food,  or  material  of  which  it  is  built. 

4th.  Life,  or  manner  of  existence. 

1st.  Structure. — Organisms  (Plants  and  Animals)  are 
composed  of  cells,  eg.,  if  a  thin  slice  of  animal  or  vegetable 
structure  be  examined  with  the  microscope  it  would  appear 
to  be  composed  of  a  great  number  of-  small  bags,  which 
in  their  earlier  stages  of  growth  are  spherical,  but  assume 
all  varieties  of  shape,  as  they  are  pressed  out  of  form  by 
being  crowded  together.  A  cell  is  composed  mainly  of 
the  four  elements  :  Carbon,  Oxygen,  Hydrogen  and  Nitro¬ 
gen.  The  first  three  of  these — Carbon,  Oxygen  and  Hy¬ 
drogen — exist  in  all  organic  cells,  while  the  fourth — Nitro¬ 
gen — is  found  only  in  animal  structure  and  the  seed  and 
coloring  matter  of  plants.  Although  the  form  and  ap¬ 
pearance  of  cells  admit  of  no  distinction,  there  is  a  special 
life  peculiar  to  each  species  of  plant  and  animal,  that 
governs  their  arrangement  and  invariably  produces  a 
structure  similar  to  that  from  which  they  originated. 

The  living  is  different  from  the  dead  cell.  The  mate¬ 
rial  of  the  dead  cell  can  be  taken  up  by  the  animal  and 
worked  over  into  the  living  cell,  but  the  plant  requires  its 


ORGANIC  AND  INORGANIC  MATTER. 


13 


partial  separation  before  it  can  take  it  up.  This  we  shall 
hereafter  find  to  be  a  chief  point  of  difference  between 
plants  and  animals.  Every  organism,  that  we  call  alive, 
is  composed  of  both  living  and  dead  cells.  The  living 
cells  are  those  that  are  in  a  formative  state,  and  are  em¬ 
ployed  in  building  the  various  parts  of  the  structure ; 
while  all  parts  that  are  finished,  and  are  not  in  the  process 
of  formation,  are  composed  of  what  we  may  call  dead 
cells. 

In  the  resolution  of  these  into  simpler  compounds,  or 
the  elements  of  which  they  are  made,  the  force  that  held 
them  together  is  given  forth  in  the  form  of  physical  or 
chemical  force  ;  but  these  forces  are  unable  to  reconstruct 
the  cell ;  hence  vital  force,  the  only  one  capable  of  build¬ 
ing  an  organic  structure,  exists  in  the  living  cell  alone. 

Inorganic  matter ,  on  the  other  hand,  is  not  composed  of 
cells,  and  hence  does  not  evince  the  results  of  vital  action. 
It  is  made  up  of  the  accretion  of  infinitesimal  particles, 
called  atoms ,  in  three  degrees  of  familiarity,*?*,  e. : 

1.  In  a  positive  attraction  for  each  other — forming  a 
Solid — the  degree  of  attraction  of  the  particles  determining 
the  hardness  of  the  solid.  Every  kind  of  inorganic  matter 
permitted  freely  to  solidify  without  restraint,  will  assume 
a  definite  form  peculiar  to  itself  called  a  Crystal. 

2.  The  atoms  being  in  a  negative  state  to  each  other, 
and  so  freely  yielding  to  every  influence  as  a  Liquid. 

3.  In  which  the  atoms  repel  each  other,  as  a  Gas  or 
Vapor,  the  latter  (vapor)  capable  of  being  reduced  to  a 
liquid  or  solid  by  cold  or  pressure,  as  carbonic  acid  gas, 
the  vapor  of  water,  &c.,  and  the  former  (fixed  gas)  not 


14 


ORGANIC  AND  INORGANIC  MATTER. 


reducible  to  a  liquid  by  any  degree  of  cold  we  are  ac¬ 
quainted  with. 

2d.  Origin. — Organisms  commence  their  existence  as  a 
single  cell,  which  (except  among  the  lowest  forms  of  plants 
and  animals)  bear  no  resemblance  whatever  to  the  struc¬ 
tures  they  are  to  build,  and  arranged  by  the  special  vital 
force  of  each  kind,  construct  the  countless  forms  of  plant 
and  animal  structure  according  to  the  fixed  and  definite 
patterns  of  beings  from  which  they  sprang. 

This  vitality  is  transmitted  down  from  parent  to  off¬ 
spring  in  an  unremitted  chain,  and  creative  power  alone  is 
capable  of  calling  forth  a  new  organism  from  inorganic 
matter,  or  of  relighting  the  flame  when  once  totally  ex¬ 
tinguished.  Inorganic  forms  are  neither  built  of  cells  nor 
commenced  from  a  single  cell ;  but  are  constructed  by  the 
accretion  of  homogeneous  particles  from  without. 

The  minutest  microscopic  crystal  may  be  of  the  same 
form  as  the  largest  one  of  the  same  material. 

3d.  Food,  or  Material  of  Construction. — Organisms 
are  capable  of  taking  and  working  into  their  own  struc¬ 
ture  materials  of  different  kinds.  In  other  words  they  are 
heterogeneous  in  their  composition ;  while  inorganic  mat¬ 
ter,  in  assuming  the  forms  of  crystals,  is  homogeneous,  or 
makes  use  of  one  kind  alone,  though  several  others  may 
be  imbedded  in  it,  <?//.,  a  crystal  of  salt  or  quartz  may 
imbed  in  itself,  or  have  commingled  with  it,  several  other 
substances  by  mechanical  union  ;  but  nothing  but  salt  or 
quartz  can  be  of  avail  in  the  forma  ion  of  a  crystal  of 
either  one  :  while  a  plant  or  an  animal  will  take  to  itself 
as  food  and  incorporate  into  its  own  being  a  variety  of 


ORGANIC  AND  INORGANIC  MATTER. 


15 


substances  united  together  by  the  three-fold  power  of 
physical,  chemical  and  vital  force. 

The  plant  will  take  from  the  atmosphere  carbonic  acid 
gas,  and  from  the  soil,  water,  with  various  minerals  dis¬ 
solved  in  it,  and  from  these,  construct  its  numerous  cells 
and  organs. 

The  animal  will  take  these  elements,  already  bound  to¬ 
gether  by  the  plant,  and  reconvert  them  into  its  own 
structure. 

The  manner  of  arrangement  of  the  material  of  growth 
of  the  organic  and  inorganic  is  different  The  organism 
grows  from  within ,  the  inorganic  mass  from  without. 

In  the  interior  of  the  plant  or  animal,  the  food  is 
prepared  for  the  building  of  the  structure,  and  thence 
distributed  to  the  several  parts.  But  it  is  on  the  out¬ 
side,  and  that  directly  from  without,  that  the  particles 
are  added  for  the  construction  of  the  crystal  or  concre¬ 
tion  of  inorganic  matter. 

4th.  Life,  or  Manner  of  Existence. — The  inorganic 
mass  is  stable ,  or,  in  other  words,  does  not  readily  tend 
to  change  or  decomposition,  while  the  organic  structure 
is  continually  changing  during  its  life,  and  is  ever  on 
the  point  of  breaking  up  its  combinations  and  return¬ 
ing  to  its  original  elements. 


16 


DIVISIONS  OF  INORGANIC  MATTER. 


CHAPTER  IV. 

DIVISIONS  OF  INORGANIC  MATTER. 

Inorganic  matter  may,  for  convenience,  be  considered 
under  the  divisions  of  Elements,  Metals ,  Minerals  and 
Rocks. 

This  grouping  is,  in  a  manner,  arbitrary  ;  established 
more  for  convenience  than  from  natural  differences. 
We  call  an  element  that  which,  by  either  chemical  or 
mechanical  means,  we  are  unable  to  resolve  into  any 
simpler  materials ;  but  future  efforts  may  be  able  to 
separate  some  that  we  now  call  elements,  into  yet  others, 
or  show  that  several  that  we  term  such  are  but  differ¬ 
ent  forms  of  the  same  element. 

Elements  combine  with  each  other  in  two  ways,  i.e., 
1st,  mechanical  mixture  and  2d,  chemical  union ;  pro¬ 
ducing  in  each  an  entirely  different  product. 

Mechanical  mixture  consists  of  a  mere  commingling 
of  the  elements,  each  element  continuing  unaltered  in 
the  mixture,  the  same  as  a  measure  of  corn  and  beans 
may  be  mixed  together,  and  the  grains  of  each  remain 
whole  and  unchanged. 

Such  is  the  mixture  of  the  elements  oxygen  and 
nitrogen,  in  the  formation  of  the  atmosphere. 

Chemical  union  is  an  intimate  combining  of  the  ele¬ 
ments  in  such  a  way  that  the  product  is  totally  different 
from  either.  While  mechanical  mixture  may  be  insti- 


DIVISIONS  OF  INORGANIC  MATTER. 


17 


tuted  between  any  and  all  elements,  chemical  union 
will  take  place  only  when  there  is  a  special  attraction 
between  the  elements,  called  chemical  affinity,  and  that, 
as  stated  above,  only  under  certain  favoring  circumstan¬ 
ces,  as  moisture  or  heat,  eg.,  hydrogen  and  oxygen, 
though  commingled  together  in  the  right  proportions,  at 
a  low  temperature,  furnish  merely  a  mechanical  mix¬ 
ture  ;  if  the  temperature  be,  however,  raised  to  a  cer¬ 
tain  point,  they  will  immediately  and  violently  combine 
with  each  other  chemically,  and  form  a  product,  water, 
wholly  different  in  all  its  characters  from  either. 

Pure  metals  are,  indeed,  also  elements,  and  cannot  be 
resolved  by  chemical  or  mechanical  means  into  simpler 
ingredients.  Yet  few  are  obtained  unassociated  in  some 
slight  degree  with  other  elements. 

Minerals  are  produced  by  the  chemical  association  of 
elements,  as  quartz  from  silicon  and  oxygen ;  water  from 
hydrogen  and  oxygen. 

Rocks,  in  the  full  signification  of  the  term,  include  any 
and  all  masses  of  elements,  metals  or  minerals,  mechani¬ 
cally  commingled  together,  whether  in  the  solid,  liquid  or 
gaseous  condition,  as  granite,  the  sand  heap,  the  soft  mud 
of  the  river  bank,  or  the  atmosphere. 


18 


DIVISIONS  OF  ORGANIC  MATTER. 


CHAPTER  V. 

DIVISIONS  OF  ORGANIC  MATTER. 

Organisms  are  divided  into  the  two  kingdoms  of  Plants 
and  Animals  ;  and  the  first  question  that  occurs  to  us  in 
relation  to  them  is  :  What  is  the  difference  between  the 
plant  and  the  animal  ? 

The  points  of  resemblance  we  have  observed  as  consti¬ 
tuting  the  characteristic  features  of  organic  structure. 

It  is  often  stated  that  the  distinguishing  feature  is,  that 
animals  are  endowed  with  the  powers  of  motion  and  feel¬ 
ing,  or  sensation,  while  plants  are  destitute  of  both. 
These  differences  exist  only  in  the  higher  grades  of  each 
kingdom  ;  but  as  we  descend  to  the  lower  ranks  we  find 
this  rule  wholly  at  fault,  or  even  misleading  us  ; — a  large 
proportion  of  the  lower  animals  are  partially  or  wholly 
destitute  of  feeling,  while  many  microscopic  plants  sustain 
a  rapid  and  energetic  motion  ;  as  the  Volvox-globator,  and 
some,  as  the  Sensitive  Plant  and  Venus  Ely-trap,  evince  a 
spasmodic  action,  resulting  from  a  kind  of  a  sensitiveness, 
which,  though  not  the  same,  is  seemingly  akin  to  that  of 
the  lower  animals.  The  fundamental  difference  between 
the  plant  and  the  animal  consists  in — 

1.  Their  respective  kind  of  work  /  and 
2  Their  food. 

It  is  the  work  of  the  plant  in  the  economy  of  nature 
to  store  up  force,  It  is  the  province  of  the  animal  to 
spend  it. 


Divisions  or  organic  matter. 


19 


The  physical  and  chemical  force  expended  in  the  living 
and  moving  of  the  animal,  are  first  laid  up  in  the  growing 
plant. 

In  the  living  cell,  vital,  physical  and  chemical  forces 
are  conjointly  at  work  ;  the  vital  force  of  the  plant  is 
capable  of  la)ing  up  or  storing  away  the  physical  and 
chemical  force,  and  the  life  of  the  animal  is  dependent  on 
this  force,  bound  up  by  the  plant,  for  its  forces  of  motion. 

Thus  plants  are  the  conservators  of  the  force  that  all 
animals  are  ever  expending  in  the  functions  of  life  and 
motion. 

From  this  it  is  evident  that  there  must  be,  as  indeed 
there  is,  a  difference  in  the  kind  of  food  required  and 
taken  by  each  kingdom. 

Plants  require  and  can  take  only  that  as  food  which  is 
inorganic,  while  every  animal,  from  the  microscopic  ani¬ 
malcule  to  the  human  system,  requires  and  can  subsist 
only  on  food  that  has  first  passed  through  the  construc¬ 
tive  agency  of  vegetable  life  and  been  made  into  a  plant. 

By  this  definition  of  food,  we  designate  that  from  which 
can  be  evolved  motion  in  the  living  animal ;  inorganic 
substances  are  necessary  in  large  proportions  as  auxiliaries 
to  food,  as  water  and  other  minerals,  but  from  these  the 
living  and  moving  powers  of  the  animal  cannot  be  ob¬ 
tained. 

While  the  plant  can  assimilate  only  inorganic  food,  it 
cannot  take  any  of  it  in  its  simplest  elemental  state,  eg., 
carbon,  though  the  chief  constituent  of  plant  structure  can¬ 
not  be  taken  up  by  the  plant  in  its  simple  state,  but  has 


20 


DIVISIONS  OF  ORGANIC  MATTER. 


to  be  first  chemically  combined  with  oxygen  in  the  forma¬ 
tion  of  carbonic  acid  gas  :  and  so  also  nitrogen,  though 
ever  bathing  the  plant  in  its  free  state  in  the  ocean  of 
atmosphere  that  it  lives  in,  cannot  be  taken  up  by  the 
leaf,  and  the  plant  will  wither  and  die  for  the  want  of  it, 
unless  presented  to  the  roots  dissolved  in  the  water  in  its 
binary  condition  of  ammonia. 

Oxygen  and  hydrogen  are,  also,  ever  present  elements 
of  plant  structure,  but  are  received  chiefly  in  their 
chemically  combined  condition  of  water. 

There  is  also  a  difference  in  the  way  in  which  plants 
and  animals  take  up  their  food.  The  plant  receives  it 
into  its  system  through  the  skin  wall  of  its  cells  by 
osmose  /  while  the  animal  invariably  first  takes  the 
food  into  an  interior  cavity,  permanently  located  or  ex¬ 
temporized  at  the  time,  as  in  some  animalcules,  and 
then  subjects  it  to  a  chemico- vital  process  of  solution 
called  digestion,  before  it  is  fit  to  be  absorbed  by  the 
system. 

We  have  thus  reviewed  the  plan  on  which  the  dif¬ 
ferent  departments  of  nature  are  arranged,  and  observed 
that  throughout  the  whole  there  is  an  intimate  con¬ 
nection  . 

While  this  general  review  of  the  entire  field,  gives  us, 
as  it  were,  a  bird’s-eye  view  of  nature,  and  is  indispens¬ 
able  for  an  introduction  to  the  proper  study  of  any  of 
its  special  departments,  each  one  of  its  branches  has 
methods  of  study  peculiar  to  itself. 

The  numberless  facts  of  nature  are  beyond  the  capa¬ 
city  of  any  mortal  mind ;  but  these  methods  of  study, 


DIVISIONS  OF  ORGANIC  MATTER. 


21 


to  a  certain  degree,  are  easily  and  quickly  attainable 
by  all. 

To  carry  out  this  to  the  extent  of  the  foundation  we 
have  laid,  would  require  a  separate  treatise  on  each  of 
the  special  sciences  ;  but  we  shall  choose  that  branch  in 
which  are  evinced  most  of  the  laws  and  phenomena  of 
nature. 

Zoology,  or  the  study  of  the  structure  and  life,  classi¬ 
fication,  and  distribution  and  relations  of  the  animal 
kingdom,  is  the  only  science  that  presents  a  compen¬ 
dium  of  all  departments  of  nature — of  physical,  chemi¬ 
cal  and  vital  force,  and  of  organic  and  inorganic 
matter. 

W e  shall,  therefore,  next  proceed  to  an  observance  of  the 
Methods  of  Study  of  the  department  of  natural  history 
pertaining  to  animals. 


22 


METHODS  OF  STUDY - SCIENCE  OF  ZOOLOGY. 


CHAPTEE  YI. 

METHODS  OF  STUDY - SCIENCE  OF  ZOOLOGY. 

The  animal  kingdom  may  be  studied  in  relation — 

1st.  To  its  functions  and  structure. 

2d.  Its  Classification  and  Natural  History. 

3d.  Its  Distribution  and  Eelations  in  Time,  or  Geologi¬ 
cal  History. 

Any  one  of  these  departments,  as  evinced  in  even  a 
small  order  or  family  of  animals,  would  furnish  field  and 
material  enough  to  occupy  a  lifetime  of  patient  labor ;  but 

the  object  of  this  volume  is  to  present  an  Outline  Sketch 
of  the  methods  by  which  the  study  of  these  departments 
may  be  commenced. 

The  specialist  would  not  find  here  what  he  may  need  to 
aid  him  in  furthering  his  research ;  but  it  is  hoped  the 
general  student  or  reader  may  have  as  it  were  a  bird’s-eye 
view  of  the  entire  field,  with  its  prominent  outlines  mapped 
out  clearly  before  him :  on  any  special  portion  of  which, 
having  first  scanned  the  whole  realm,  he  may  afterwards 
alight  and  view  its  wonders  and  beauties  with  a  closer 
ken. 

We  shall  now  proceed  to  a  consideration  of  each  of 
these  three  departments  separately. 

1st  Functions  and  Structure . 

The  structure  of  an  animal  is  always  arranged  according 
to  the  requirements  of  its  functions.  In  the  principles  of 


METHODS  OF  STUDY-— SCIENCE  OF  ZOOLOGY. 


23 


of  animal  mechanics,  the  simplest  mechanism  is  employed 
in  performing  any  work,  and  hence  we  find  the  anatomy 
of  an  animal  made  according  to  its  physiology  or  work. 

The  place  an  animal  lives  in,  its  methods  of  locomotion, 
the  climate  it  must  endure,  its  kind  of  food,  and  the  way 
it  will  have  to  procure  it,  the  medium  it  will  have  to 
breathe,  whether  water  or  air,  the  amount  of  pressure  it 
was  intended  to  sustain,  its  duration  of  life,  and  the  spe¬ 
cial  part  in  the  economy  of  nature  it  was  intended  to  fill 
all  separately  and  conjointly,  determine  not  only  the  ex¬ 
ternal  appearance  of  an  animal,  but  also  the  entire  ana¬ 
tomy  of  the  interior. 

The  structure  of  animals  is  not  according  to  a  number 
of  patterns,  but  though  there  exist  hundreds  of  thousands 
of  different  forms,  apparently  in  no  way  connected,  yet  all 
these  are  variations  of  a  single  plan,  or  model  system. 

All  animals  have  their  organs  developed  out  of  this 
model  plan,  according  to  the  requirements  of  their  life  ; 
even  the  microscopic  animalcule,  whose  shapeless  body 
seems  destitute  of  organs,  has  enough  of  this  plan  deve¬ 
loped  in  itself  to  meet  the  wants  of  its  plant-like  life. 

The  following  is  a  table  of  the  organs  of  a  model 
animal,  arranged  according  to  its  functions  : 


24 


METHODS  OP  STUDY— SCIENCE  OP  ZOOLOGY* 
Table  II. 


Animal  ^ 
Functions 


Motion. 


’  1 .  Skeleton  for 
Protection, 
Leverage, 
and 

Support, 

as  Bones , 
Shell ,  or 
Skin, 

2.  Muscles. 


Vegetative 

Functions 


,Y  .  C  Nervous  System, 
sensation  .  <  < 

'  Organs  ol  Sense. 


Organs  of  the 
Digestive 
System  ; 
Respiratory,  or 
Breathing 
System  ; 
Circulatory 
System. 


Touch, 

Taste, 

Smell, 

Hearing, 

Smht. 


"  Nutrition  . < 


j'  Organs  of  Generation  ; 

-  Generation  A  Methods  of  Generation  ; 

[_  Development  of  Embryo. 

It  belongs  to  the  province  of  Comparative  Anatomy  to 
trace  out  these  organs  in  their  relations  to  the  above  model 
plan ;  but  we  shall  make  a  brief  review  of  each  function 
and  its  special  organs. 


GENERATION. 


25 


CHAPTER  VII. 

GENERATION. 

1st.  Generation  is  the  function  by  which  the  young 
of  animals  are  produced  and  the  species  continued. 

As  the  classification  and  history  of  animals  depends 
very  largely  upon  their  methods  of  reproduction,  it  is 
essential  that  we  should  get  a  clear  conception  of  this 
subject  before  we  proceed. 

We  would  consider  in  this  connection — 

1st.  The  Methods  of  Generation. 

2d.  The  Generative  Product  and  its  Development. 

1st.  Methods  of  Generation. — All  animals  are  pro¬ 
duced  from  parents  like  themselves,  and  so  continue 
their  own  kind  in  unvarying  succession. 

The  next  table  gives  us  an  outline  of  the  differences 
in  this  function  : 


GENERATION  on  REPRODUCTION. 


TABLE  OF  METHODS  OF  GENERATION. 


Non-Sexual  < 


Table  III. 


Fissiparous.  .  .  <{ 


Gemmiparous 


Sexual 


Hermaphrodite . 


Dioecious. 


Parent  splits  —  Each 
part  a  new  animal : 

1.  Transverse. 

2.  Longitudinal. 

3.  Irregular. 

Parent  splits  and  dis¬ 
charges  the  young. 

Budding  upon  the 
parent  stock. 

Separated  buds. 
Gemmae  or  Sporules. 

1.  On  all  parts  of 
the  body. 

2.  On  one  part  or 
organ  only. 


Both  sexual  organs  on 
one  individual. 

1.  Self  impregna¬ 
tion. 

2.  Mutual  impreg¬ 
nation. 

Sexes  Distinct. 

Laying  eggs  which  are 
hatched. 

1.  internal  fecun¬ 
dation. 

2.  Internal  fecun¬ 
dation. 


Eggs  hatched  within 
the  maternal  body. 
Mammiferous, 

Suckling  the  young. 
Ovo-  Viviparous  1.  Monotrematous. 

2.  Marsupial. 

3.  Placental,  or 
strictly  Vivipa- 


GENERATION. 


27 


2d.  The  germ,  is  produced  from  the  parent  animal  in 
three  ways,  i.e.  : 

1.  By  the  spontaneous  division  of  one  individual  into 
two  or  more  parts,  each  of  which  may  form  a  distinct 
animal  exactly  resembling  the  parent — called  Fissiparous 
reproduction. 

2.  By  the  production  of  bitcls,  either  on  the  surface  or 
within  the  parent — Gemmiparous  reproduction. 

8.  By  the  production  of  eggs,  which  may  be  matured 
within  or  without  the  body  of  the  parent — Oviparous  re¬ 
production. 

The  study  of  the  development  of  the  germ  or  embryo 
is  called  Embryology. 

Much  that  would  be  of  value  under  this  head  the 
size  of  this  volume  compels  us  to  omit.  More  of  it  will, 
however,  l  e  brought  on  with  the  descriptions  of  the 
types  and  classes  of  animals. 


28 


DIGESTION. 


CHAPTER  VIII. 

DIGESTION. 

Digestion  consists  of  the  process  by  which  the  indi¬ 
vidual  animal  is  built  up,  and  its  waste  of  life  and 
motion  repaired. 

The  digestive  apparatus,  unlike  that  of  plants,  where  it 
is  always  on  the  surface,  among  animals,  is  always  in  the 
interior,  and  called  the  Alimentary  Canal  or  Cavity. 

It  is  of  a  great  variety  of  forms  and  sizes,  from  a  mere 
sack  or  bag,  made  at  the  moment  of  use,  and  then  again 
closed  up  to  give  place  to  others  in  different  parts  of  the 
body ;  as  among  numbers  of  the  animalculae  (Amoeba, 
sponge  animals,  &c.,)  to  the  elaborate  and  complete  system 
of  mouth-organs,  such  as  tongue,  teeth,  salivary  glands, 
pharynx,  oesophagus,  stomachs,  intestines,  excretory  or¬ 
gans,  absorbents,  glands  of  secretion  and  excretion,  as 
liver,  pancreas,  spleen,  &c. 

The  structure  and  condition  of  the  digestive  system  indi¬ 
cate,  more  than  any  other  part,  the  habits  and  requirements 
of  life  of  an  animal.  The  structure  of  the  tongue  and 
teeth,  the  size  and  muscular  strength  of  the  alimentary 
canal,  especially  the  stomach,  and  the  power  of  the  attend¬ 
ant  organs  to  make  their  special  secretions,  indicate  defi¬ 
nitely  the  kind  of  food  an  animal  requires,  and  hence  the 
kind  of  life  it  leads,  for  these  organs  are  ever  constructed 
with  special  reference  to  these  conditions  of  life. 


DIGESTION. 


29 


To  a  study  of  this  system,  then,  we  are  indebted,  not  only 
for  an  acquaintance  with  much  of  the  greatest  importance 
and  interest  in  relation  to  modern  animal  life,  but  also  for 
our  entire  sum  of  knowledge,  of  the  life  and  habits  of  the 
countless  number  of  animals,  that  lived  on  the  earth  before 
the  appearance  of  man. 


30 


RESPIRATION. 


CHAPTER  IX. 

RESPIRATION. 

Respiration  or  Breathing  consists  of  the  two-fold  func¬ 
tions  : 

1st.  The  evolution  or  giving  off  of  carbonic  acid  gas  ; 
and 

2nd.  The  absorption  of  oxygen. 

The  causes  of  these  are,  that  in  the  economy  or  life  of 
the  animal,  there  are  continually  disintegrating  changes 
going  on,  that  produce  carbonic  acid  gas;  which  is  poisonous 
to  animal  life,  and  is  gotten  rid  of  chiefly  through  the 
medium  of  respiration  ;  and  in  the  next  place,  oxygen  is  an 
indispensable  element  for  the  construction,  motion  and 
warmth  of  the  being,  and  in  the  degree  that  the  animal 
is  active  and  energetic  in  its  motions,  warm  in  its  tempera¬ 
ture,  and  delicate  and  subtle  in  its  structure,  will  it  require 
the  functions  of  respiration. 

The  animal  structure  is  continually  decaying  during  life, 
as  well  as  in  death ;  and  breathing  is  the  act  by  which 
most  of  the  product  of  this  decay  is  removed  from  the  sys¬ 
tem.  “  Every  development  of  muscular  force,  or  of  nervous 
power,  is  accompanied  by  a  destructive  change  in  a  certain 
amount  of  tissue,  to  which  change  the  presence  of  oxygen 
is  essential,  and  one  of  the  products  of  the  union  of  oxygen 
with  the  elements  of  the  nervous  and  muscular  substances 
is  carbonic  acid.” 


RESPIRATION . 


31 


Respiration  is  the  only  function,-  through  which  this  sup¬ 
ply  of  oxygen,  as  well  as  the  removal  of  carbonic  acid  gas, 
is  effected ;  and  though  the  higher  warm-blooded  animals 
are  much  more  dependent  on  it  than  the  lower,  no  ani¬ 
mal  life,  whether  of  the  land  or  water,  can  be  supported 
without  it  for  any  length  of  time. 


32 


ORGANS  OF  RESPIRATION. 


CHAPTER  X. 

ORGANS  OF  RESPIRATION. 

The  Respiratory  Organs  consist  fundamentally  of  a 
permeable  or  porous  membrane ,  through  which  the  free 
oxygen  of  the  air,  whether  from  the  atmosphere,  or  dis¬ 
solved  in  water,  and  the  gasses  of  the  animal  fluid  may 
change  places  with  each  other,  by  the  mechanical  law  of 
the  interchange  of  gasses  and  liquids,  called  Osmose. 

In  some  of  the  lower  animals  this  is  accomplished  solely 
by  the  delicate  skin  of  the  entire  body,  on  the  inner  side 
of  which  are  the  animal  fluids,  on  the  outer  the  air  dis¬ 
solved  in  the  water  in  which  the  animal  lives.  But  as  we 
ascend  in  rank  in  the  animal  kingdom,  we  find  this  deli¬ 
cate  expanded  membrane  confined  to  special  parts  of  the 
body,  and  two  systems  of  organs  added  auxiliary  to  it, 
i .  e. : 

1st.  A  set  of  organs  for  circulating  the  animal  fluid  along 
the  inner  surface  of  the  membrane. 

This  alone  is  added  in  those  water  animals  that  have  the 
power  of  free  motion. 

2d.  All  air  breathing  animals,  and  some  stationary 
aquatic  animals,  have  a  set  of  organs  for  changing  the 
material  they  breathe,  either  air  or  water. 

These  three  sets  of  respiratory  organs  exist  in  all  stages 
of  development,  and  adaptation  to  the  different  kinds  of 
animal  life — as  ciliary  appendages,  branchiae,  gills,  lungs, 
etc, 


CIRCULATION* 


33 


CHAPTER  XI. 

CIRCULATION. 

Circulation  in  the  animal  is  the  function  by  which  the 
fluids  of  the  body  are  moved  about,  for  the  purposes  of  pu¬ 
rification,  or  of  building  up  the  structure  and  repairing 
waste. 

This  may  be  either  directly  through  the  thin  walls  of 
the  bags  and  organs,  or  along  sets  of  tubes  for  exporta¬ 
tion  called  Arteries ,  and  importation  called  Veins,  from  a 
central  propelling  organ  called  the  Heart . 

The  degree  and  kind  of  circulation  indicates  markedly 
the  character  of  the  animal,  and  is  one  of  the  chief  fea¬ 
tures  on  which  zoological  classification  is  founded. 

While  digestion  and  respiration  prepare  the  nutriment 
for  the  body,  circulation  bears  it  to  all  parts  of  the  system, 
and  supplies  it  to  all  the  organs  and  their  tissues  as  need¬ 
ed,  and  removes  away  from  them  the  refuse  product  of 
their  decay,  and  the  waste  of  heat  and  motion. 

The  structure  of  animals  in  relation  to  the  circulation 
may  be  arranged  according  to  the  following  table  : 


34 


CIHCTTLATTON* 


Table  of  Methods  of  Circulation. 

Table  IY. 


].  Animals  without  hearts  or  circulating  tubes. 


2.  Animals  with 
a  single  set 
of  circula  t  - 
ing  tubes  .  . 


f  Without  heart 

J  !  Cold-blooded,  or 

]  With  heart  of  a  single  f  Hfematocrya. 
lobe  or  valve.  .  .  .  J 


3. 


Circulating 
tubes  in  the 
two  distinct 
sets  of  arte¬ 
ries  and 
veins  .... 


”  Heart  of  two  lobes  or-> 
valves  . 

Heart  of  two  or  three 
*4  lobes  or  valves.  .  .  - 


Cold-blooded,  or 
Haematocrya. 


Heart  of  four  lobrs 
or  valves . 


']  Wann-blooded, 
[>  or 

J  Haematotlierma. 


These  four  functions  of  Generation ,  Digestion ,  Respi¬ 
ration  and  Circulation ,  are  called  vegetative,  because 
they  are  essential  alike  for  the  life  of  both  plants  and 
animals.  Those  of  sensation  and  motion  are  peculiar  to 
animals  alone,  and  hence  are  called  Animal  Functions. 


SENSATION, 


35 


CHAPTEK  XII. 

SENSATION. 

The  special  functions  of  sensation  are  those  of — 

1.  Nervous  Action, 

2.  Touch, 

3.  Taste, 

4.  Smell, 

5.  Hearing, 

6.  Sight. 

Nervous  Action  is  the  means  by  which  the  organs,  or 
parts  of  the  animal  body,  reciprocate  with  each  other  in 
the  relations  of  sensation,  or  feeling  and  motion,  whether 
voluntary  or  involuntary.  In  the  lowest  members  of  the 
animal  kingdom  this  nerve,  or  vital  power,  is  equally  dis¬ 
tributed  through  all  ..parts  of  the  body,  and  is  transmitted 
from  one  portion  to  another  by  the  direct  contact  of  the 
cells  and  organs,  there  existing  no  distinct  sets  of  nervous 
organs.  As  we  ascend  in  rank,  however,  distinct  systems 
of  nervous  organs  are  found  with  increasing  perfection, 
forming  the  chief  basis  of  zoological  classification ,  and 
the  ladder  on  which  the  rank  of  the  animal  kingdom  is 
arranged. 

The  nerve  systems  of  animals  are  arranged  according 
to  five  plans,  which,  we  shall  hereafter  find,  give  rise  to 
the  five  great  types  or  branches. 


36 


SENSATION. 


Table  V. 

1.  Nervous  system,  without  any  distinct  nerve  organs. 

2.  Nervous  system,  consisting  of  a  nerve  thread  around 
the  stomach,  with  branching  nerve  filaments. 

3.  Nervous  system  of  nerve  bunches,  called  Ganglia, 
arranged  chiefly  about  the  stomach,  and  their  connecting 
and  branching  nerves. 

4.  Nerve  system  of  a  row  of  nerve  bunches,  or  Gang¬ 
lia,  extending  from  one  extremity  of  the  body  to  the 
other,  with  their  connecting  and  branching  system  of 
nerves,  called  the  Ganglionic  or  Sympathetic  System. 

5.  Nerve  system,  consisting  of  a  governing  nerve  mass, 
of  two  parts  (Cerebrum  and  Cerebellum),  located  in  the 
head,  from  which  extends  the  entire  length  of  the  trunk  a 
nerve  chain ,  called  the  Spinal  Cord,  with  its  branching  sets 
of  nerves  /  with  which  is  associated  the  Ganglionic  or 
Sympathetic  System. 

The  nervous  systems  may  act  independently,  as  in  feel¬ 
ing,  or  in  a  special  way  peculiar  to  themselves,  called  Elec¬ 
trical  or  Magnetic,  in  connection  with  the  Muscular  Sys¬ 
tems,  in  motion,  whether  voluntary  or  involuntary,  and 
in  the  several  functions  of  life  peculiar  to  the  animal,  and 
as  agents  in  the  higher  faculties  of  volition,  instinct, 
thought,  and  roason. 


FIVE  SENSES. 


37 


CHAPTER  XIII. 

^  FI  YE  SENSES. 

The  organs  of  special  sense  are  those  of 
Touch, 

Taste, 

Smell, 

Hearing, 

Sight. 

These  are  found  by  no  means  equally  distributed  through¬ 
out  the  animal  kingdom ;  indeed,  most  of  the  lowest  types 
of  animals  are  almost,  if  not  quite,  destitute  of  them  ;  but 
as  we  ascend  in  rank,  and  find  the  nervous  systems  more 
developed,  so  also  these  organs  of  special  sense  keep  pace 
with  them  in  their  development  and  perfect  action. 

Touch 

Is  the  sense  by  which  animals,  through  their  surfaces,  gain 
a  knowledge  of  the  bodies  surrounding  them,  or  the  con¬ 
ditions  in  which  they  may  exist. 

It  is  the  physiological  parent  of  the  other  senses,  being 
not  only  the  first  educator  of  them  in  man,  but  the  first 
one  evinced  among  the  lower  animals.  Thus,  while  of  all 
the  senses,  it  is  the  simplest  and  the  least  confined  to  any 
one  part  of  the  animal,  and  the  most  general  in  its  action, 
V*  it  is  at  the  same  time  the  most  direct,  positive  and  certain 
of  them  all. 


38 


FIVE  SENSES. 


It  might  be  considered  under  the  heads  of  Tactile  Dis¬ 
crimination,  Temperature  and  Muscular  Sense. 

The  first  two,  Tactile  Discrimination  and  Temperature, 
are  exercised  through  the  surface  of  the  body,  and  the 
third,  Muscular  Sense,  through  the  action  of  the  muscles. 


Taste 

Is  the  sense  by  which  animals  are  enabled  to  perceive  the 
differences  of  flavor  in  their  food,  and  make  a  proper 
selection  thereof.  It  is  invariably  located  in  the  mouth, 
in  the  organ  called  the  tongue,  though  the  tongue  is  by  no 
means  always  possessed  of  the  function  of  taste. 

Among  most  of  the  lower  animals  the  tongue  is  merely 
a  prehensile  organ  for  catching  and  holding  the  food,  and 
is  wholly  destitute  of  the  powers  of  taste.  Among  great 
numbers  of  the  lowest  members  of  the  animal  kingdom 
there  is  an  entire  want  of  any  organ  that  may  be  called  a 
tongue,  and,  in  many  cases  indeed,  of  any  mouth-organs 
whatever. 

Smell 

Is  the  sense  by  which  animals  are  capable  of  taking 
knowledge  of  odors,  and  is  chiefly  a  guide,  as  well  as  taste, 
in  the  selection  of  food.  Most  of  the  lower  animals  seem 
either  to  be  destitute  of  it,  or  to  have  it  merged  with  the 
functions  of  touch. 

Among  the  higher  animals  the  nose  and  the  nostrils  are 
the  organs  of  smell,  and  greatly  vary  in  their  form  and 
development. 

Hearing 

Is  the  sense  by  which  animals  are  enabled  to  receive  and 
distinguish  sounds.  The  organ  of  hearing  consists  funda- 


FIVE  SENSES. 


39 


mentally  of  an  elastic  membrane  to  receive  the  vibrations 
of  the  air,  and  a  set  of  nerves  to  impart  a  knowledge  of 
those  vibrations  to  the  chief  nerve  centres. 

The  lowest  members  of  the  animal  kingdom  are  desti¬ 
tute  of  any  organs  of  hearing  whatever ;  and  the  highest 
members  have  a  wonderful  and  delicate  mechanism  in  the 
ear,  comprised  in  three  chambers,  i.e.,  the  anterior ,  middle , 
and  posterior  chambers.  Between  these  two  extremes 
exist  organs  of  all  degrees  of  complexity  and  perfection. 

Sight , 

Or  vision,  is  the  sense  by  which  animals  are  enabled  to  re¬ 
ceive  impressions  from  light.  The  organs  of  vision  con¬ 
sist  fundamentally  of  one  or  more  transparent  refractive 
membranes  for  lenses,  to  collect  together  the  rays  of  light 
and  form  the  image,  together  with  an  expanded  nerve  to 
receive  it.  In  the  lowest  animals — when  it  exists  at  all,  the 
entire  eye  consists  of  a  mere  speck,  capable  only  of  receiv¬ 
ing  light,  but  not  form  or  color.  From  this  elementary 
form  upward,  we  find  all  stages  and  degrees  of  develop¬ 
ment,  to  the  wonderful  visual  organs  of  the  birds  and 
mammals. 

We  do  not  propose  to  take  up,  at  length,  in  this  connec¬ 
tion  the  development  of  the  organs  of  sense  ;  that  would 
be  the  special  work  of  a  treatise  on  comparative  anatomy 
and  physiology.  We  would  merely,  in  our  methods  of 
study,  outline  as  it  were,  the  several  functions  and  organs 
to  be  taken  into  consideration  in  a  review  of  animal  me¬ 
chanism. 

Proceeding  from  the  Organs  of  Sensation  we  would  next 
sketch,  in  brief,  those  of  Motion , 


40 


MOTION. 


CHAPTER  XIV. 

MOTION. 

Motion ,  or  movement  in  the  animal  mechanism,  is  of 
two  kinds,  Voluntary  and  Involuntary ;  and  quite  dif¬ 
ferent  in  its  character  from  the  movement  of  plants.  It  is 
executed  through  two  sets  of  organs,  first,  Muscles ,  and 
second,  Endo ,  or  Exo-  Skeleton,  for  leverage,  protection 
and  support ;  but  in  many  of  the  lower  animals,  a  muscu¬ 
lar  system  alone  exists,  and  even  that,  indeed,  often  of  a 
very  weak  and  loose  texture. 

The  skeleton  is  either  external,  as  the  shell  of  the  crab 
or  lobster,  or  the  hard  skin  of  the  insect,  and  is  called 
Exo- Skeleton ;  or  is  internal,  having  the  muscles  attached 
to  its  exterior,  as  the  bony  skeleton  of  the  vertebrae,  and 
is  called  Endo-Skeleton. 

An  outline  of  the  model  or  Archetype  Endo-Skeleton 
will  be  given  in  connection  with  the  characteristic  features 
of  vertebrates. 

As  has  already  been  said,  the  structure  of  the  animal 
is  the  basis  of  the  classification  adopted  by  this  volume. 


CLASSIFICATION. 


41 


CHAPTEE  XV. 

CLASSIFICATION. 

Thor©  are  two  systems  according  to  which  plants  and 
animals  are  classified :  one  called  the  Natural,  and  the 
other  the  Artificial  system. 

The  artificial  system  arranges  plants  and  animals  ac¬ 
cording  to  their  appearance  and  external  conditions,  with¬ 
out  reference  to  their  structural  relations,  hut  it  is  one  of 
great  uncertainty  and  ever  subject  to  changes  and  varia¬ 
tions.  It  was  adopted  by  the  older  zoologists,  and  hence 
we  find  their  systems  ever  conflicting  with  each  other. 

The  end  sought  after  by  the  artificial  system,  is  merely 
to  name  objects,  for  which  oftentimes  the  commonest  points 
of  external  appearance  are  alone  observed ;  and  animals 
and  plants  that  are,  according  to  their  structure,  wide  apart, 
are  grouped  together,  and  those  that  may  be  closely  related 
are  placed  far  asunder ;  thus  answering  the  purposes  of  a 
dictionary  or  table  of  reference. 

The  natural  system,  on  the  other  hand,  is  founded 
wholly  on  points  of  structural  resemblance  and  difference. 

Those  animals  that  are  alike  in  the  most  prominent  fea¬ 
tures  of  structure,  though  they  may  differ  in  a  number  of 
lesser  ones,  it  groups  together  in  the  great  departments  of 
Branches  and  Types,  differing  from  each  other  in  the  most 
important  features  of  their  anatomy.  Those  of  each  of 
these  types  that  resemble  one  another  in  some  other  lesser 
points  of  structure,  but  differ  from  a  number  of  other 


42 


CLASSIFICATION. 


groups  of  the  same  type  on  those  very  points,  it  still  further 
divides  into  classes,  and  these,  by  other  successive  grada¬ 
tions  of  resemblance  and  difference,  into  Orders,  Families, 
Genera,  and  Species. 

This  gradation  of 

Types, 

Classes, 

Orders, 

Genera,  and 

Species, 

Forms  the  nomenclature  of  the  natural  system  of  classi¬ 
fication. 

The  last  two  (Genus  and  Species)  combined  together 
forms  the  specific  name  of  an  animal.  The  Generic  pre¬ 
ceding  the  Specific  name,  as  Smith  John,  instead  of  John 
Smith,  e.g .,  canis  familiar  is,  the  common  or  familiar  dog, 
instead  of  familiaris  cards.  This  method  is  one  that 
greatly  economises  the  number  of  words  used  in  naming 
the  animal,  as  comparatively  a  few  names,  variously  com¬ 
bined  and  interchanged  with  each  other,  furnish  distinctive 
terms  for  the  hundreds  of  thousands  of  animals  of  which, 
if  each  were  possessed  of  an  entirely  distinct  name,  the 
vocabulary  would  be  far  beyond  the  reach  of  any  human 
intellect,  and  an  acquaintance  with  the  members  of  even 
an  order  or  family  an  utterly  hopeless  task  ;  while  now,  a 
few  names,  that  soon  become  familiar,  are  used  over  and 
over  m  different  combinations,  under  the  several  larger 
groups,  and  so  combine  the  utmost  definiteness  with  the 
greatest  simplicity.  With  these  introductory  remarks  we 
will  now  enter  upon  the  second  head  or  department. 


METHODS  OF  STUDY. 


43 


CHAPTER  XVI. 

METHODS  OF  STUDY,  l.e .,  CLASSIFICATION  AND  NATURAL  HISTORY. 

Classification  of  the  animal  kingdom,  or  systematic 
zoology ,  relates  to  the  arrangement  of  animals  in  their 
several  groups  of  types,  classes,  orders,  etc.,  according  to 
their  resemblance  and  difference  of  structure.  Natural 
History  is  the  science  of  descriptions  relating  to  the 
appearances,  methods  of  life,  and  habits  of  animals. 

Our  methods  of  study  shall  be,  first,  to  get  a  clear  idea 
of  the  types  and  their  points  of  distinction ;  next,  of  the 
classes  they  include ;  then,  of  the  orders,  and  so  on,  noticing 
merely  a  few  genera  and  species  in  connection  with  each 
of  these  divisions,  to  illustrate  the  structural  peculiarities 
we  may  have  under  consideration. 

The  learner  would  make  much  easier  and  quicker  pro¬ 
gress  in  the  attainment  of  an  acquaintance,  even  with  the 
details  of  classification  of  any  special  part  of  the  animal 
kingdom,  by  first  thoroughly  mastering  the  distinctive  fea¬ 
tures  of  the  larger  division  of  types,  classes  and  orders, 
and  this  method,  certainly,  is  of  the  first  importance,  if 
the  two  chief  objects  in  the  study  of  Natural  History, 
spoken  of  in  the  first  section  of  this  volume,  i.e.,  the  de¬ 
velopment  of  our  observing  powers  and  learning  the 
laws  of  nature,  are  the  ends  in  view. 

We  must,  then,  concisely  review — 

1.  The  special  and  distinctive  features  of  all  the  types ; 


44 


METHODS  OF  STUDY. 


2.  The  classes  of  each  type  ;  and 

3.  The  order  of  each  class.  The  compass  of  this 
volume  will  not,  except  in  a  few  special  cases,  permit  us  to 
proceed  beyond  the  sub-orders  and  families,  and,  indeed, 
not  in  all  cases  even  beyond  the  orders. 

The  animal  kingdom,  according  to  its  structure,  divides 
itself  into  five  great  types,  or  branches,  i.  e.,  beginning 
with  the  lowest,  as  we  shall,  in  all  cases : 

Protozoa, 

Radiates, 

Mollusks, 

Articulates, 

Vertebrates. 

€ 

We  have  chosen  to  arrange  our  tables  from  the  lowest 
upward,  because  we  are  thus  enabled  to  study  the  struc¬ 
ture  of  the  higher  groups  as  taught  synthetically,  by  the 
lower  ones. 

These  types  are  all  constructed  according  to  the  same 
plan ;  though  in  the  highest  alone  do  we  find  the  entire 
system  brought  out  as  given  in  our  review  of  Structural 
Zoology. 

Each  of  these  types,  however,  expresses  a  distinctive 
arrangement  of  the  organs  of  the  body,  and  is  built  on 
an  idea  or  method  exclusively  peculiar  to  itself. 

That  we  may  have  clearly  before  us  the  method  in  which 
our  studies  of  each  of  these  divisions  will  be  conducted,  t 
we  would  again  call  to  the  mind  of  the  student  the  table 


METHODS  OE  STUDY. 


45 


of  functions  and  organs,  as  our  studies  of  the  divisions 
shall  be  conducted  in  relation  to  each  of  these,  i.  e.: 

Generation, 

Digestion, 

Eespiration, 

Circulation, 

Nerve  Action, 

Organs  of  Sense, 

Organs  of  Movement, 

And  also  as  regards  their  general  appearance,  habits,  and 
places  of  residence. 


> 


46 


PROTOZOA. 


CHAPTER  XVII. 

PROTOZOA. - GENERATION. 

The  Type  of  Protozoa  comprises  the  lowest  and  sim¬ 
plest  organisms  in  the  animal  kingdom.  In  the  lower 
orders,  no  definite  organs  exist,  but  the  animals  present, 
under  the  microscope,  formless  and  shapeless  masses  of 
jelly,  in  which  the  various  organs  of  the  body  are  made 
for  the  occasion  at  the  tim3  they  are  needed  for  use. 

Reproductio?i  is  non-sexual.  No  distinct  sexes  have 
been  discovered  among  the  Protozoa.  They  multiply  ex¬ 
clusively  by  dividings  (fissiparous),  and  by  budding  (gem- 
miparous).  They  comprise  all  the  methods  of  fissiparous 
multiplication,  i.  e .,  by  the  parent  splitting  transversely, 
longitudinally,  or  irregularly,  or  splitting  open  and  dis¬ 
charging  the  young. 

Some  of  the  Protozoa  pass  through  several  genera¬ 
tions  in  a  few  hours,  and  their  spores  or  buds  survive 
almost  any  exposure  of  heat  or  cold,  and  may  be  even  sub¬ 
jected  to  chemical  action,  or  be  pulverised,  without  losing 
their  vitality. 

Digestion  among  the  Protozoa  is  of  the  lowest  grade, 
and  enacted  by  organs  of  the  very  simplest  structure,  con¬ 
sisting,  among  the  greater  number  of  them,  of  a  mere 
cavity,  or  depression  in  the  soft  shapeless  body,  endowed 
with  the  vital  power  to  dissolve  the  food  taken  into  it. 

The  entire  alimentary  canal  consists  of  a  mere  sack,  with 


PROTOZOA. - DIGESTION. 


47 


the  same  opening  for  entrance  and  outlet,  and  even  this 
simple  organ  has  to  be  made  at  the  time  of  use  among 
many  of  the  lower  orders ;  as  the  amoeba,  sponge  animals, 
etc.,  where,  on  the  contact  of  the  food,  a  bag  or  cavity  is 
sunk  into  the  body,  or  little  filaments  are  projected  as  arms 
that  encircle  it,  and  so  a  stomach  is  formed  of  the  part  of 
the  body  where  the  food  is  floating. 

Several  of  these  stomachs  may  be  formed  on  different 
parts  of  the  body  at  the  same  time,  which,  after  having 
performed  the  special  work  for  which  they  were  extempo¬ 
rized,  may  again  be  merged  and  lost  in  the  soft  plastic 
tissue  of  the  body,  called  Sarcode.  This  feature  led  Ehren- 
berg,  the  great  microscopist  of  Berlin,  to  call  this  type 
Polygastria,  or  many-stom ached. 

Some  others  of  this  type  have  even  a  simpler  process  of 
digestion  ;  subsisting  entirely  on  liquid  food,  they  have  need 
of  neither  stomach  nor  digestive  fluid,  and  so  absorb  their 
nutriment  directly  through  the  skin  wall  of  the  body. 

Others,  again,  are  supplied  with  a  more  elaborate  system, 
consisting  of  a  permanent  stomach,  with  tubes  of  inlet  and 
exit. 

The  existence  and  courses  of  these  organs  in  such 
minute  jelly-like  animals,  have  been  traced  under  the 
microscope,  after  they  had  been  fed  on  colored  liquids. 

Many  of  them — as  the  Stentor,  Yorticella,  Potifera — 
have  numerous  vibrating  hairs  or  cilia  around  their  mouth 
openings,  that  keep  up  a  rapid  vibration,  and  so  sustain 
the  circulation  of  a  current  of  water  through  their  stom¬ 
achs,  and  are  thus  supplied  with  the  particles  of  decaying 
matter  floating  in  the  water  that  furnish  their  food. 


48 


PROTOZOA. - RESPIRATION - CIRCULATION. 


Distinct  Respiratory  and  Circulatory  Organs  are 
usually  wanting. 

The  oxygen  is  absorbed  from  air,  dissolved  in  the  water, 
directly  through  the  entire  skin  wall  of  the  body. 

It  is  presumed  that,  in  some  of  the  higher  orders,  the 
vibratile  cilia  around  the  mouth  answer,  in  a  greater 
degree  than  the  rest  of  the  body,  the  functions  of  respira¬ 
tion. 

The  circulating  fluids  are  conducted  in  the  lowest  orders 
directly  from  cell  to  cell,  through  their  partition  walk  ; 
though,  in  the  higher,  there  are  a  few  branching,  circulat¬ 
ing  tubes,  through  which,  the  fluids  are  conducted  by  the 
contraction  and  expansion  of  the  body. 


PROTOZOA. - NERVOUS  SYSTEM - ORGANS  OF  SENSE.  49 


CHAPTER  XVIII. 

PROTOZOA. - THE  NERVOUS  SYSTEM  AND  ORGANS  OF  SENSE. 

Among  the  Protozoa  no  distinct  nervous  organs  have 
been  found,  although  they  are  evidently  possessed  of  a 
distinct  nervous  action  and  the  functions  of  some  of  the 
organs  of  sense. 

The  vital  power  is  equally  distributed  through  all  parts 
of  the  body,  to  such  an  extent  that  the  animals  will  con¬ 
tinue  ther  existence,  unharmed,  even  if  cut  into  a  number 
of  pieces  ;  each  piece  readily  fashioning  itself  into  and 
taking  up  the  life  of  a  distinct  animal.  All  the  organs  of 
sense  among  them  are  wanting,  yet  they  evidently  are 
capable  of  the  sense  of  touch  ;  but  the  entire  lining  of 
the  body  is  equally  capable  of  it,  except  among  the  higher 
orders,  which  have  many  hairs  or  cilia  around  the  mouth, 
that  seem  to  be  possessed  of  a  greater  degree  of  tactile  or 
sensitive  power  than  the  rest  of  the  body. 

Some  of  the  higher  members  of  the  type  seem  to  be 
sensitive  to  light,  but  their  powers  of  vision  extend  no 
further.  Ehrenberg  describes  some  red  spots  on  the  lin¬ 
ing  of  their  bodies  as  rudimentary  eyes,  but  this  is  not  yet 
established  as  a  fact.  They  evince  a  choice  in  the  selection 
of  their  food,  but  this  cannot  be  attributed  to  anything  like 
a  sense  of  taste,  but  rather  to  a  vital  principle,  the  same  as 
that  which  guides  the  plant  to  a  selection  of  its  food. 

That  they  are  possessed,  in  any  degree,  of  the  functions 
of  smell  and  hearing  we  have  no  evidence. 


50 


PROTOZOA. - MOTION 


Motion ,  among  a  great  many  of  this  type,  is  active  and 
constant,  although  only  a  few  of  them  are  possessed  of  even 
a  rudimentary  locomotive  apparatus.  They  are  all  of  them 
devoid  of  anything  like  a  skeleton,  either  external  or  in¬ 
ternal  ;  although  many  of  them  secrete  hard  shells,  or  cases 
of  lime  or  flint,  on  the  exterior  of  their  bodies,  which 
aggregate  and  form  masses,  often  of  great  extent.  Yet 
this  hard  covering  is  merely  a  protective  envelope,  and 
those  occupying  it  are  usually  fastened  to  one  spot. 

Except  among  some  of  the  higher  orders,  which  have 
those  vibratile  cilia  we  spoke  of,  even  distinct  muscles  are 
wanting,  and  the  little  animal  moves  by  a  contraction  and 
expansion  of  its  entire  jelly-like  mass,  or  the  incessant 
vibration  of  many  little  hairs  on  all  parts  of  the  body. 


PROTOZOA. - NATURAL  HISTORY. 


51 


CHAPTEK  XIX. 

PROTOZOA - NATURAL  HISTORY. 

The  type  of  Protozoa  includes  countless  numbers  of 
microscopic  animals,  most  of  which  are  quite  invisible  to 
the  naked  eye.  Their  numbers,  however,  exceed  all  com¬ 
putation. 

Of  the  hard  shells,  of  those  that  secrete  limy  or  flinty 
coverings,  immense  strata  of  rock  have  been  formed,  tens 
and  hundreds  of  feet  in  thickness,  and  thousands  of  square 
miles  in  extent ;  which,  by  subsequent  wrinkling,  have 
formed  lofty  mountains.  The  ocean,  in  its  broad  expanse 
and  depth,  and  all  its  branches  and  streams  ;  the  lakes  and 
rivers  of  the  land ;  the  ponds  and  little  runnels  and  ruts, 
and  even  the  mud-puddle  or  little  pocket  contained  in  the 
hollow  of  the  rock  or  a  decaying  log,  or,  indeed,  any  place 
where  we  may  find  a  drop  of  water,  if  there  is  the  least 
decaying  organic  matter  in  it,  is  found  to  contain  countless 
hosts  of  these  Protozoa. 

They  are  the  first  animals  that  were  created  on  the  sur¬ 
face  of  the  earth,  for  we  find  their  remains  in  the  lower¬ 
most  strata  that  contains  animal  fossils. 

Although  of  insignificant  size,  they  are  of  immense 
importance  in  the  life  or  economy  of  the  earth  ;  not  only  do 
the  shells  of  the  hard  covered  ones  form  great  layers  of  rocks, 
but  the  myriads  of  formless,  organless,  jelly-like  atoms  that 
swarm  in  all  waters  that  contain  the  least  decaying  organic 
matter,  act  as  scavengers,  ridding  the  waters  of  the  little 


52 


PROTOZOA. - NATURAL  HISTORY. 


putrid  masses,  that  else  would  render  them  unfit  for  sustain¬ 
ing  higher  kinds  of  life. 

The  Protozoa  all  live,  only  in  the  water,  although  their 
bodies  will  sustain  an  indefinite  amount  of  injury  without 
loss  of  life. 

The  ponds  in  which  they  swarm  may  be  dried  up,  and 
the  dust  made  up  of  their  bodies  blown  abroad  over  the 
land,  and  subjected  to  a  hundred  various  changes,  yet,  on 
the  first  application  of  sufficient  moisture,  they  will  again 
come  to  life  and  be  as  active  as  ever. 

The  type  of  Protozoa  includes  such  animals  as  the  vari¬ 
ous  kind  of  Sponges,  Chalk  Animals,  Flint  Animals, 
Amoeba,  Vorticella,  etc.,  which  we  shall  consider  hereafter. 


TYPE  OF  RADIATES. - GENERATION. 


53 


CHAPTEE  XX. 

TYPE  OF  RADIATES. 

The  type  of  Eadiates  is  characterized  from  all  others, 
by  having  the  organs  arranged  around  a  common  centre, 
from  which  the  branches  or  segments  of  the  body  radiate, 
usually  in  multiples  of  five.  They  are  all  of  them  inhabi¬ 
tants  of  the  water,  and  nearly  all  of  the  ocean  or  salt  and 
brackish  waters.  The  vital  organs  of  the  animals  are  all 
soft,  but  many  orders  of  them  secrete  and  deposit  struc¬ 
tures  of  lime  within  their  bodies,  forming  masses  called 
corals,  or  build  either  a  scaffolding  or  frame- work,  amid 
which  the  animal  lives,  as  the  star  fishes  ;  or  else  constructs 
a  shell  or  case  around  their  bodies,  composed  either  of  lime, 
and  studded  with  pencil-like  spines,  as  in  the  Sea  Urchin, 
or  as  in  the  Sea  Cucumber,  or  Synapta,  a  cartilagenous 
shell,  sometimes  even  garnished  with  hooks. 

We  may  now  proceed  to  a  review  of  the  structure  of  the 
type  of  Eadiates,  commencing  with  that  of  the  organs  of 
generation. 

Generation. 

The  Eadiates  increase  in  three  ways  : 

1st  By  dividing  into  segments  or  parts. 

2d.  By  budding. 

3d.  By  emission  from  their  bodies  at  certain  times  of  the 
year  of  great  numbers  of  spores,  or  ciliated  round  masses, 
resembling  eggs. 


54  TYPE  OF  RADIATES. - DIGESTION - RESPIRATION. 

The  last  two  are  the  most  prevalent  methods  of  multi¬ 
plication,  and  are  of  extreme  importance  m  the  life  and 
economy  of  the  animals  in  the  ocean.  The  little  spores,  or 
detached  buds,  float  freely  in  the  water,  and  so  reach  the 
places  most  conducive  to  their  life  and  growth,  and  then, 
as  they  develop,  either  continue  moving  about  in  that 
region  or  else  fix  themselves  permanently  to  the  rock,  and 
increase  to  an  indefinite  extent  by  buds  from  all  parts  of 
their  surface.  Multiplication  by  division  is  comparatively 
rare  among  them. 

Those  that  increase  by  spores  or  eggs  are  always  bi¬ 
sexual,  though  both  sexes  may  be  either  united  in  the 
same  individual,  or  exist  on  separate  ones. 

Digestion. 

The  digestive  apparatus  of  the  Radiates  is  extremely 
simple  in  all  except  the  highest  class.  It  usually  consists 
of  a  mere  sack,  with  but  one  opening,  into  which  the  food 
is  drawn  by  numerous  arms  or  tentacles  placed  around  it. 

These  tentacles  are  endowed  with  great  contractile 
power,  so  that  they  can  be  drawn  back  into  the  body 
or  projected  out  to  great  length,  at  the  option  of  the 
animal.  They  are  also  often  armed  with  a  powerful  sting, 
and  an  acrid  liquid  that  is  capable  of  producing,  even  on 
the  human  surface,  a  smarting,  and  in  some  cases  a  severe 
inflammation  ;  but,  among  the  animals  on  which  they  feed, 
it  acts  as  a  paralyzing  or  deadening  agent.  The  bodies  of 
some  appear  as  mere  sacks  or  stomachs,  with  the  few 
soft  radiating  organs  of  the  body  arranged  around. 

Respiration  among  the  Radiates  is  altogether  and  invari¬ 
ably  aquatic.  None  of  them  are  capable  of  breathing  in 


type:  op  radiates.— a  iiteuLATiotf. 


55 


the  atmosphere.  The  oxygen  is  taken  from  the  dissolved 
air  in  the  water  either  by  the  entire  skin  wall  of  the  body 
or  by  the  numerous  tentacles  that  surround  the  mouth. 

Circulation  is  carried  on  by  a  scarcely  more  complex  sys¬ 
tem  than  among  the  Protozoa.  There  are  tubes  that  branch 
out  from  around  the  stomach  and  convey  the  chyle  or  digest¬ 
ed  food  to  all  parts  of  the  body,  but  there  is  no  distinct  sys¬ 
tem  of  arteries  and  veins,  nor  is  the  fluid  propelled  through 
its  tubes  by  means  of  a  muscular  heart. 


56  RADIATES. - NERVOUS  SYSTEM - ORGANS  Of  SENSE. 


CHAPTER  XXI. 

RADIATES - NERVOUS  SYSTEM  AND  ORGANS  OF  SENSE. 

A  delicate  nerve  filament  surrounding  the  mouth  or 
stomach,  opening  and  sending  off  branches  into  the  several 
parts  of  the  body,  especially  where  the  tentacles  or  arms 
are  fastened,  is  the  only  rudimentary  set  of  nervous  organs 
found  among  the  Radiates. 

And  the  Organs  of  Sense  are  in  a  similar  state  of  devel¬ 
opment.  The  sense  of  touch  apparently  is  equally  distri¬ 
buted  over  the  body.  Among  the  members  of  the  highest 
class,  at  the  ends  of  certain  nerve-lines,  are  organs  which 
are  capable  of  taking  knowledge  of  light,  but  not  of  form 
or  color.  The  remaining  functions  and  organs  of  sens'; 
seem  to  be  entirely  wanting. 

The  Organs  of  Locomotion  are  distributed  under  a  wide 
variety  of  forms.  Many  of  them,  as  the  coral  animals, 
are  anchored  to  one  spot  during  the  whole  of  their  ex¬ 
istence,  and  only  such  of  their  numbers  as  are  thrown  off 
from  the  parent  animals  in  the  form  of  spores,  are  capable 
of  swimming  around  and  changing  their  habitation,  and 
that,  only  during  the  earliest  stages  of  their  lives. 

Others,  as  the  Star  Fishes  and  Sea  Urchins,  are  only 
capable  of  crawling  along,  slowly  and  deliberately,  at  the 
bottom  of  the  water,  over  the  rocks  and  rubbish,  amid 
which  they  live  ;  while  yet  others  again,  as  the  Jelly  Fishes, 
dance  along  through  the  waters  or  float  lightly  upon  its 
surface. 


RADIATES. - NATURAL  HISTORY. 


57 


The  special  set  of  organs  requisite  for  each  of  these  will 
be  taken  into  consideration  in  connection  with  the  several 
classes  of  Radiates 

The  solid  formation  within  the  coral  animals  can 
scarcely  be  called  a  skeleton,  as  it  is  more  properly  a 
deposit  in  the  body  as  it  grows  old. 

In  the  highest  kind  of  Radiates  alone  do  we  find  what 
may  be  classed  as  a  skeleton,  in  which  the  growing  walls 
of  the  Se a  Urchin  and  Star  Fish,  furnish  the  first  instance 
of  a  growing  skeleton.  Among  most  of  the  Jelly  Fishes, 
however,  neither  a  growing  skeleton  or  even  a  living  de¬ 
posit  is  found  ;  but  the  body  consists  of  a  mere  mass  of 
jelly,  in  which  not  even  muscular  fibres  are  visible,  and 
which  perform  their  motions  by  a  simultaneous  contrac¬ 
tion  and  expansion  of  their  entire  body  or  disk. 

The  higher  classes,  however,  which  have  distinct  arms, 
are  possessed  of  delicate  masses  of  muscular  fibres. 

The  natural  history  of  the  Radiates,  as  we  have  already 
observed,  pertains  entirely  to  the  water.  Countless 
myriads  of  them  have  inhabited  the  ocean,  ever  since  the 
first  appearance  of  animal  life  on  the  earth  ;  they  swarm 
in  the  seas  of  all  latitudes,  and  fill  the  two  important  parts 
in  the  economy  of  the  ocean  life,  of  purifying  the  waters 
and  of  furnishing  food  for  hosts  of  higher  animals. 


58 


TYPE  OF  MOLLUSKS. - GENERATION. 


CHAPTER  XXII. 

TYPE  OF  MOLLUSKS. - GENERATION  AND  NUTRITION. 

Members  of  the  type  of  Mollusks  are  distinguished 
from  the  two  preceding  types,  by  the  greater  distinctness 
of  their  nervous  system  and  organs  of  sense,  by  the  per¬ 
fection  of  the  circulatory  and  breathing  systems,  and  the 
first  introduction  and  simplest  evincement  in  the  animal 
kingdom,  of  the  dual  or  double  arrangement  of  the  struc¬ 
ture,  called  the  “  bilateral  system ,”  in  which  all  the  chief 
organs  of  the  body  are  arranged  in  pairs. 

Their  general  structure  will  present  itself  in  the  follow¬ 
ing  review  of  Molluscan  organization. 

Generation  is  bi-sexual,  although  both  sexes  are,  among 
many  species,  combined  in  the  same  individual. 

In  passing  up  to  the  Mollusca,  we  lose  sight  altogether 
of  every  trace  of  Gemmiparous  and  Fissiparous  reproduc¬ 
tion. 

We  have  no  illustrations  of  their  increase  by  divi¬ 
sion  into  segments,  or  by  budding.  They  are  produced 
wholly  by  eggs,  which,  in  a  few  cases,  however,  are  de¬ 
posited  within  the  body  of  the  parent  and  retained  within 
the  shell  until  hatched,  and  thus  living  young  are  given 
forth.  The  eggs  of  some  are  distinct,  and  protected  by  a 
shell  that  is  either  albuminous  and  flexible,  or  calcareous 
and  brittle. 

Others  again  connect  their  eggs  into  masses,  or  spread 


'.TYPE  OF  MOLLUSKS. — -NUTRITION. 


59 


them  out  in  the  form  of  a  strap  or  ribbon,  coiled  up  spirally 
like  a  watch-spring,  attached  by  one  of  its  edges.  Some 
enclose  their  eggs  in  numbers  together,  within  little  tough 
capsules,  which  they  string  together  on  a  chain,  or  cluster 
around  a  stem,  like  bunches  of  grapes,  or  arrange  in  radi¬ 
ating  masses. 

Most  usually,  the  young  are  passed  from  the  egg  in  a 
form  not  in  the  least  resembling  the  parent,  and,  after  a 
series  of  changes,  in  the  adult  state  alone  are  like  their 
parents  in  all  points. 

Such  immature  changes,  through  which  the  young  of 
many  animals  pass,  is  called  the  larval  state ,  and  the 
young  themselves  the  Larva 

Digestion ,  and  its  attendant  functions  of  respiration 
and  circulation,  especially  the  last,  are  in  a  much  higher 
degree  of  development  among  the  Mollusca  than  in  any  of 
the  preceding  types.  Among  some,  the  mouth  is  unarmed, 
except  by  soft  feelers,  but  among  others,  powerful  and 
sharp  jaws  flank  it  on  either  side.  We  would  observe, 
before  speaking  of  what  is  called  the  lingual  tube  of  some 
of  these  Mollusks,  that  among  the  invertebrates,  the  word 
tongue  is  used  to  designate  any  prehensile  organ  of  the 
mouth,  without  reference  to  its  being  the  organ  of  taste. 
Among  many  of  the  Mollusks,  a  tube  extending  back  from 
the  mouth,  and  lined  its  whole  length  with  teeth,  number¬ 
ing  in  some  instances  several  thousands,  is  called  the  lin¬ 
gual-tube. 

These  teeth  assume  all  varieties  of  forms  as  well  as 
numbers. 

►Sometimes  the  tongue  forms  a  short  semicircular  ridge 


60 


TYPE  OE  MOLLTTSXS. - NUTRITION. 


contained  between  the  jaws,  at  others  it  is  extremely  elon¬ 
gated,  and  its  folds  extend  backward  to  the  stomach, 
while  yet  in  others  its  folds  are  longer  than  the  whole  body. 

Some  Mollusks  are  possessed  of  organs  resembling  the 
gizzard  of  a  fowl,  in  which  the  food  is  received  and  ground. 
Others  are  yet  further  supplied  with  a  crop,  in  which  the 
food  is  received  and  held  as  it  is  swallowed  until  subjected 
to  digestion.  The  liver  is  always  large  in  the  Mollusca ; 
its  secretion  is  derived  from  arterial  blood,  and  is  poured 
either  into  the  stomach  or  the  intestines.  Many  are  even 
furnished  with  developed  salivary  glands,  and  some  have 
a  rudimentary  pancreas,  and  also  special  glands  for  the 
secretion  of  colored  liquids  of  the  most  delicate  tints. 


MOLLUSKS. - RESPIRATION  AND  CIRCULATION. 


61 


CHAPTER  XXIII. 

MOLLUSKS. - RESPIRATION  AND  CIRCULATION. 

Respiration  among  the  Mollusks  is  of  both  kinds — 
aquatic  and  aerial ;  among  those  that  live  in  the  water  it  is 
accompanied  by  pairs  of  gills,  called  branchiae,  which  are 
exposed  to  the  changing  water,  either  by  merely  floating 
in  it,  or  by  having  the  water  led  in  and  out  through  a 
special  pair  of  tubes,  called  siphons,  which  are  drawn  out 
to  considerable  length  in  those  that  live  in  the  sand. 
Others  breathe  directly  through  their  mantle  or  covering. 

The  depth  of  water  in  which  the  Mollusks  live  is  fixed 
partly  by  the  amount  of  oxygen  they  need,  and  partly  by 
the  adaptation  of  the  body  to  endure  pressure. 

The  air-breathing  Mollusks  are  possessed  of  lungs,  or 
air  chambers,  formed  by  the  folding  back  of  the  mantle, 
in  the  interior  of  which  are  arranged  the  breathing  organs, 
consisting  of  merely  a  permeable  set  of  air  bags,  and  a 
circulatory  system  to  supply  and  remove  the  blood,  the  air 
being  renewed  with  sufficient  rapidity  merely  by  the  law 
of  diffusion. 

The  respiratory  system  is  of  very  great  importance  in 
the  economy  of  the  Mollusks,  and  a  fundamental  point  in 
their  classification. 

Circulation  is  carried  on  among  the  Mollusks  by  a  sys¬ 
tem  of  organs  of  much  greater  development  than  among 
either  of  the  lower  types. 


62 


MOLLUSKS. - NERVOUS  SYSTEM. 


This  type  is  not  possessed  of  any  distinct  absorbent  sys¬ 
tem,  but  the  product  of  digestion  (chyle),  passes  into  the 
general  abdominal  cavity,  and  thence  into  the  numerous 
veins  of  the  body.  They  are  possessed  of  a  distinct  heart 
of  two  chambers,  arteries  and  veins,  and  so  have  a  circula¬ 
tory  system  of  much  greater  development  than  the  Protozoa 
and  Padiates,  and,  indeed,  than  even  the  larger  number  of 
the  Articulates. 


The  Nervous  System. 

Among  the  Mollusca,  the  chief  portion  of  the  nervous 
system  consists  of  a  ring  of  nervous  matter  surrounding 
the  throat,  thickened  out  in  places  into  nervous  bunches, 
called  ganglia,  and  from  which  proceed  nerve-cords  to  all 
parts  of  the  body. 

Organs  of  Sense. 

Every  one  of  the  organs  of  sense  exist  among  some  of 
the  Mollusks,  though  in  various  degrees  of  perfection. 
Their  eyes  vary  from  mere  spots  on  the  sides  of  the  mantle, 
that  are  scarcely  capable  of  taking  knowledge  of  light,  as 
among  such  as  the  Oyster,  to  the  most  elaborate  visual 
organs  of  the  Cuttle  Fish.  The  lowest  of  the  type  do  not 
evince  any  organs  of  hearing,  but  among  the  higher  orders 
the  middle  chamber  chiefly  is  developed. 

The  sense  of  Smell  is  evidently  possessed  by  the  Cuttle 
Fishes,  and  by  the  class  to  which  the  Snails  and  other  uni¬ 
valve  shells  belong.  Snails  seek  and  select  their  food  by 
this  sense.  Slugs  are  attracted  by  special  odors,  and  many 
of  the  ocean  Mollusks  may  be  taken  with  animal  baits. 

The  sense  of  Taste  is  also  indicated  rather  by  the  habits 
of  the  animal,  and  their  choice  of  food,  than  by  the  struc¬ 
ture  of  a  special  organ,  for,  as  we  have  already  observed, 


MOLLUSKS.— OKGANS  OF  SENSE.  63 

that  which  is  called  the  tongue,  is  an  organ  intended  for 
the  seizing  and  preparing  of  the  food,  and  not  for  the 
functions  of  taste. 

The  sense  of  Touch ,  in  the  lowest  class,  is  equally,  dis¬ 
tributed  over  the  entire  covering  of  the  body,  called  the 
mantle. 

Such  is  the  case  among  the  Clams,  Oysters,  and  other 
bivalves;  but,  among  the  higher  classes  of  the  type,  special 
organs,  called  tentacles,  are  appropriated  to  it.  Thus  all  the 
Snails  and  other  univalves  have  flexible  feelers,  or  arms, 
from  the  head ;  two  of  which  are  for  the  purposes  of 
touch,  while  the  other  pair  support  the  eyes.  Among 
members  of  the  highest  class  there  exist  several  arms 
around  the  head,  which  are  endowed  with  organs  of  touch. 

Thus  we  find  the  special  organs  of  sense,  as  well  as  the 
general  structure  of  the  nervous  system,  among  the  type 
of  Mollusks  is  altogether  on  a  higher  plan  than  that  of 
either  of  the  two  lower  types,  the  Protozoa  or  Padiates. 


64 


MOLLUSKS. - INTEGUMENT. 


CHAPTEE  XXIY. 

MOLLUSKS. - INTEGUMENT  OR  SHELL  OF. 

We  next  proceed  to  consider  the  organs  of  locomotion 
and  of  protection,  among  the  type  of  Mollusks. 

The  muscles  are  mostly  attached  directly  to  the  skin, 
or  mantle,  of  the  body,  and  are  of  rather  a  flaccid  char¬ 
acter. 

A  few  muscles,  however,  are  always  of  a  more  solid  and 
compact  character.  Such  are  the  strong  muscles  that, 
among  the  Oysters  and  Clams,  connect  together  the  two 
valves  of  the  shell,  and  open  and  close  them  at  will,  and 
the  projecting  foot  of  the  Snail,  or  the  powerful  prehensile 
arms  of  the  Cuttle  Fish  and  Nautilus. 

All  the  Mollusks  are  devoid  of  an  endo- skeleton,  except 
the  Cuttle  Fishes,  where  is  found  the  first  appearance  of 
anything  like  an  internal  organ,  of  support  and  protection 
in  the  Cuttle  Fish  bone. 

Most  of  the  Mollusks  manufacture,  however,  an  exo- 
skeleton ,  or  shell,  as  it  is  called,  which  is  constructed  in  a 
wonderful  and  delicate  manner  on  the  outside  of  the  body, 
as  it  enlarges. 

The  mantle,  or  skin  covering  of  the  body,  is  the  organ 
that  builds  the  shell.  Its  structure  is  commenced  around, 
the  young  animal  before  it  is  passed  from  the  egg-case 


MOLLUSKS. - INTEGUMENT. 


65 


and  is  enlarged  and  thickened  as  the  animal  grows  larger. 
Molluscan  shells  are  composed  of  three  layers  or  parts  : 

1.  Limy  layer. 

2.  Nacreous  layer. 

3.  Periostracum. 

The  limy  layer  is  the  greater  part  of  most  shells.  It  is 
composed  of  carbonate  of  lime,  and  built  along  the  outer 
side  and  edge  as  the  animal  increases  in  size.  These  layers 
are  added  one  to  the  other,  as  may  be  seen  in  a  transverse 
section  of  an  onion,  and  each  of  these  layers  are  composed 
of  a  series  of  closely  fitting  columns,  usually  hexagonal, 
which,  themselves,  are  again  composed  of  a  series  or  pile 
of  plates. 

The  nacreous  layer  is  deposited  on  the  inside  of  the 
living  shell  by  a  liquid  secreted  by  the  body.  It  is  com¬ 
posed  of  very  delicate  plates,  laid  partly  over  each  other, 
and  presenting  sometimes  the  appearance  of  a  coat  of  por¬ 
celain  varnish,  at  others  that  of  a  sheet  of  burnished  silvery 
metal,  while  yet  others  are  ire  descent,  with  a  beautiful  play 
of  colors. 

This  layer  answers  as  a  protecting  cushion  for  the  soft 
body  that  lies  within  it,  and  forms  what  we  are  so  exten¬ 
sively  acquainted  with  in  the  arts,  under  the  name  of 
mother-of-pearl,  and  is  also  used  as  a  lining  for  any 
foreign  object,  as  a  grain  of  sand  ;  or  a  wound  that 
may  happen  within  the  body  of  the  animal,  and  this 
forms,  by  the  addition  of  layer  above  layer,  what  we  call 
a  Pearl. 

The  periostracum  or  epidermis  is  an  outer  coat  of 
animal  matter  of  various  appearances ;  on  some  it  is 


66 


MOLLUSKS. - INTEGUMENT. 


thin  and  transparent,  on  others  again,  quite  thick  and 
opaque. 

It  is  thick,  leathery  and  olive-colored  in  all  fresh  water 
shells,  and  all  Arctic  sea  shells.  It  gives  color  to  a  number 
of  land  shells. 

On  some  shells  it  is  silky,  or  fringed  with  hairs  ;  on 
others  it  is  thick  and  rough,  like  coarse  cloth  ;  and  on  yet 
others,  drawn  out  into  long  beard-like  filaments. 

The  periostracum  is  a  living  part  of  the  shell,  and  protects 
it  against  the  injury  of  water- wear  and  chemical  action. 

After  death,  however,  it  soon  cracks  and  crumbles  away, 
often  exposing  beneath  it  a  most  exquisitely  colored  and 
variegated  surface. 

This  coloring  of  the  shell  is  effected  by  little  paint  bags 
placed  along  the  edge,  from  which  the  patches  and  lines 
of  pigment  are  interwoven  into  the  shell  as  it  is  built. 
Those  shells,  particularly  of  the  tropics,  that  live  nearer  the 
surface  of  the  water,  are  the  most  beautifully  colored. 

Having  thus  reviewed  the  chief  structural  peculiarities 
of  the  type  of  Mollusks,  we  shall  now  proceed  to  say  a  few 
words  in  relation  to  their  Natural  History ,  or  general 
economy. 

They  are  the  first  air-breathing  animals  we  have  yet,  in 
our  studies,  reviewed.  They  have  existed  in  the  oceans 
from  the  earliest  zoological  ages,  and  have  continued  in 
immense  numbers  ever  since,  forming  in  some  places,  of 
their  shells  alone,  layers  of  rocks  hundreds  of  feet  thick 
and  scores  and  hundreds  of  miles  in  extent. 


MOLLUSKS. - INTEGUMENT. 


67 


They  are  more  intimately  connected  with  the  economy 
of  human  life  than  either  the  Radiates  or  Protozoa. 

Their  bodies  are  extensively  used  as  food,  and  their 
shells  for  the  manufacture  of  articles  of  use  and  orna¬ 
ment. 


68 


ARTICULATES. - ARRANGEMENT  OF  RINGS. 


CHAPTEE  XXY. 

ARTICULATES - ARRANGEMENT  OF  RINGS. 

We  will  next  proceed  to  consider  the  distinctive  features 
of  the  type  of  Articulates. 

The  type  of  which  we  are  now  to  speak  comprises  by 
far  the  greatest  number  of  species  in  the  entire  animal 
kingdom.  They  swarm  in  countless  myriads  in  the  ocean, 
on  the  land,  under  its  waters,  and  in  the  air ;  and  in 
places  that  seem  absolutely  untenable,  even  to  the  lowest 
kinds  of  animal  life,  as  the  interior  of  the  bodies  of  other 
living  animals,  and  the  springs  of  boiling  water.  Nor 
is  their  structure  less  varied  and  interesting ;  according  to 
their  diverse  habits  and  habitations,  their  forms  assume  an 
infinite  variety  of  modifications,  though  all  are  built,  as 
the  other  types,  on  one  general  plan.  It  is  of  this  model, 
or  general  structure,  that  we  will  now  proceed  to  speak. 

The  Articulates  are  distinguished  by  the  body  being 
composed  of  a  chain  of  rings. 

There  are  three  plans,  or  methods,  of  arrangements  of 
these  rings : 

1st.  A  uniform  chain  of  rings,  as  among  the  worms. 

2d.  Eings  arranged  in  cephalo-thorax  and  abdomen,  as 
in  Lobsters  and  Spiders. 

3d.  Eings  arranged  as  among  insects,  in 
Head, 

Thorax, 

Abdomen. 


ARTICULATES. - ARRANGEMENT  OF  RINGS. 


69 


1.  Those  of  the  first  plan  merely  have  the  rings  of  the 
body  attached  to  each  other,  as  a  string  of  beads  ;  and, 
among  the  lowest  of  these,  all  the  rings  are  possessed  of  an 
equal  amount  of  vitality,  so  that,  if  they  be  severed  into  as 
many  pieces  as  there  are  rings  in  the  body,  each  piece 
might  reproduce  itself,  or  grow  into  a  complete  animal, 
such  as  the  Tape  Worm. 

2.  Those  in  which  the  rings  are  arranged  into  a  ceph- 
alo-thorax  and  abdomen ,  have  the  rings  of  the  front 
welded  more  or  less  together,  into  one  piece,  on  vdiich  are 
located  the  organs  of  the  mouth,  of  the  senses,  and  of 
locomotion. 

3.  The  arrangements  of  the  rings  into  the  head,  thorax 
and  abdomen  exists  among  the  highest  members  cf  the 
Articulates.  The  head  is  possessed  of  the  largest  nerve 
mass  of  the  body,  the  organs  of  the  senses  and  of  the 

mouth. 

The  thorax  is  axis  of  the  body,  composed  usually  of 
three  rings,  joined  closely  together,  and  to  it  are  fastened 
the  organs  of  locomotion,  both  wings  and  legs. 

And  the  abdomen  is  composed  of  rings,  connected 
together  with  a  flexible  skin,  or  membrane,  and  possessed 
of  the  chief  organs  of  digestion,  respiration,  circulation, 
generation  and  oviposition. 


t 


70 


ARTICULATES. - NUTRITIVE  GROANS. 


CHAPTEE  XXVI. 

ARTICULATES - NUTRITIVE  ORGANS. 

We  will  now  proceed  to  study  the  Articulates  in  relation 
to  their  structure.  Reproduction  is  chiefly  by  means  of 
eggs ;  the  sexes  in  most  cases  are  distinct ;  the  young  is 
passed  from  the  egg  usually  in  an  immature  condition, 
called  larva,  which  often  passes  through  many  stages  of 
transformation  before  reaching  the  adult  state.  Some  will 
multiply  themselves  by  breaking  or  dividing  into  parts — 
fissiparations. 

Such  is  the  case  with  the  Entozoa  or  intestinal  worms. 
The  Articulates  multiply  with  extreme  rapidity. 

Digestion  among  the  Articulates  has  a  wider  range  of 
action  than  among  any  other  animals.  As  members  of 
this  type  are  found  in  nearly  every  place,  they  are  also 
capable  of  taking  and  digesting  every  kind  of  food  that 
any  animal  can  live  on. 

There  is,  accordingly,  a  great  variation  in  the  structure 
of  the  digestive  organs ;  from  a  mere  sack,  without  any 
special  openings  of  entrance  or  exit — absorbing  its  nutri¬ 
ment  like  a  plant  cell  from  its  entire  surface,  as  in  the 
intestinal  worms — to  an  elaborate  alimentary  canal,  con¬ 
sisting  of  mouth  and  prehensile  organs,  oesophagus,  stom¬ 
ach,  intestines,  liver  and  other  auxiliary  organs,  as  among 
the  insects,  which  we  shall  consider  at  length  when  we 
come  to  a  reviewal  of  that  class. 

Respiration  among  the  Articulates  is  both  aquatic  and 
aerial.  Myriads  of  them  spend  their  entire  brief  existence 


ARTICULATES. - NUTRITIVE  ORGANS. 


71 


in  the  water ;  as  many  others  again,  are  exclusively  deniznes 
of  the  air  ;  while  yet  others  live  in,  and  breathe  water  dur¬ 
ing  their  earlier  life  or  larval  condition,  and  are  exclusively 
air-breathing  during  their  adult  state,  as  certain  insects, 
such  as  the  Dragon  Fly,  Mosquito,  Gnat,  etc. 

The  respiratory  organs  are  essentially  of  three  kinds  : 

1st.  Among  the  lower  orders  of  the  worms,  the  entire 
surface  of  the  body  acts  the  part  of  a  breathing  organ  ; 
such  are  always  inhabitants  of  the  water,  or  of  moist  places. 

2d.  The  body  is  provided  with  tubes,  which  are  either — 
as  among  some  of  the  higher  worms — turned  outward,  and 
fastened  about  the  body  in  tufts,  or  are  turned  inward,  and 
branch  as  spiracles,  through  the  rings  of  the  body.  Such 
we  find  to  be  the  case  among  the  insects. 

3d.  In  the  abdomen  exist  air-bags  called  lungs,  as 
among  the  Spiders  ;  these  are,  however,  different  from  the 
lungs  of  Vertebrates,  in  that  they  are  simple  sacks,  and 
not  collections  of  air  and  blood  cells. 

Circidation  is  less  complete  in  this  type  than  among  the 
Mollusks.  The  muscles  and  organs  of  the  body  are  con¬ 
stantly  bathed  in  blood,  and  even  the  insects  have  not  any 
definite  circulating  tubes,  as  arteries  and  veins. 

A  contractile  tube  along  the  back  of  the  body  answers  to 
a  heart,  and  moves  the  blood  from  one  part  of  the  system 
to  another.  The  blood,  however,  among  some  of  the  active 
insects,  as  the  Bee,  is  of  a  warmer  temperature  than  among 
any  of  the  lower  types,  and,  indeed,  even  than  among 
many  of  the  higher  types,  as  Fishes,  and  other  cold¬ 
blooded  Vertebrates. 


72 


ARTICULATES. - THE  NERVOUS  SYSTEM. 


CHAPTER  XXYII. 

ARTICULATES - THE  NERVOUS  SYSTEM. 

Although  the  organs  of  circulation,  among  the  Articu¬ 
lates,  are  of  a  lower  grade  than  among  the  Mollusca, 
the  greater  development  of  their  nervous  system  entitles 
them  to  a  higher  rank  in  the  animal  kingdom. 

The  nervous  system  consists  of  a  nerve  cord  or  chain, 
extending  the  entire  length  of  the  body,  along  which,  at 
regular  distances,  are  fastened  nerve-centres,  or  masses, 
called  ganglia,  and  about  each  ganglionic  mass  is  con¬ 
structed  a  ring  or  segment  of  the  body,  through  which  the 
nerves  of  feeling  and  motion  branch  from  the  centre  gang¬ 
lion.  The  nerves  of  feeling,  however,  even  among  the 
Articulates,  are  but  in  a  rudimentary  condition.  These 
animals,  as  well  as  all  the  other  Invertebrates,  seem  almost 
destitute  of  the  sensations  of  pain. 

It  is  true  that  in  poetry  we  are  told,  “  The  poor  beetle 
“  that  we  tread  upon,  in  corporeal  sufferance,  feels  a  pang 
“  as  great  as  when  a  giant  dies but  anatomy  and  true 
philosophy  tell  us  differently:  “  Pain,  nature’s  kind  har- 
“  binger  of  mischief,  is  only  inflicted  for  wise  and  import- 
“  ant  purposes ;  either  to  give  warning  of  the  existence 
“  of  disease,  or  as  a  powerful  stimulus,  prompting  to 
“  escape  from  danger.” 

These  animals,  incapable  of  remedying  the  one  or  avoid¬ 
ing  the  other,  not  only  ever  exposed  to  destruction  and 
death,  but  created  for  the  purpose  of  preying  on  each  other 


ARTICULATES. - ORGANS  OF  SENSE.  73 

by  tlie  myriad,  are  kindly  denied  the  feeling  of  acute  pain. 
Their  nervous  organization  still  further  denies  the  existence 
of  it,  save  in  a  low  degree. 

The  central  chain  of  ganglia,  among  the  Articulates,  can 
perceive  external  impressions  and  originate  motion,  bat  not 
feel  pain  ;  that  is,  a  perception  of  the  brain ,  and  may  be 
acute,  as  the  body  is  under  a  special  nerve  mass  located  in 
the  head,  as  among  the  Vertebrates. 

How  far  the  feeling  of  pain  is  actively  developed  in 
these  animals  may  be  deduced  from  every-day  observation. 
The  Fly,  seized  by  the  leg,  will  leave  its  limb  behind  and 
alight,  with  apparent  unconcern,  to  regale  upon  the  nearest 
sweets  within  its  reach  ;  the  Caterpillar  seems  to  enjoy  a 
tranquil  existence  while  the  larvae  of  the  Ichneumon 
hatched  in  its  body  devours  its  very  viscera;  and  in  the 
Crustacea,  of  so  little  importance  is  the  loss  of  a  leg,  that 
the  Lobster  will  throw  off  its  claws  if  alarmed  by  the 
report  of  a  cannon.  The  arrangement  of  the  nervous  sys¬ 
tem  among  the  Articulates  is  the  reverse  of  that  among 
Man  and  the  other  Vertebrates. 

Organs  of  Sense. 

Organs  of  Sense ,  though  of  a  lower  grade  than  among 
the  Vertebrates,  are,  in  the  highest  orders,  of  a  more 
elaborate  and  delicate  structure  than  among  any  of  the 
preceding  types.  There  is,  however,  a  great  range  in  the 
development  of  these  organs,  from  the  lower  worms  to  the 
insects;  and  as  we  shall  treat  of  each  of  these,  somewhat 
in  detail,  in  connection  with  the  classes  of  Articulates,  our 
remarks  in  relation  to  them  here  shall  be  brief. 

The  sense  of  Touch  among  the  two  higher  classes  is  seated 
chiefly  in  feelers  from  the  head,  called  Autense,  Among 


74 


ARTICULATES. - ORGANS  OF  MOTION. 


the  lowest  class  of  worms,  what  there  is  of  the  sense  is 
distributed  over  the  entire  surface  of  the  body. 

Taste  evidently  exists  among  many  of  this  type,  for  they 
evince  a  choice  and  selection  in  their  food  ;  but,  as  among 
the  Mollusks,  the  tongue  is  not  usually  invested  with  the 
sense  of  taste,  but  is  moie  generally  a  prehensile  organ 
for  the  purpose  of  catching  and  retaining  the  food. 

The  senses  of  Smell  and  Hearing  are  both  in  a  rudi¬ 
mentary  condition,  and  the  organs,  through  which  they 
act,  undetermined,  though  usually  referred  to  the  antense 
or  palpi  of  the  head.  Smell,  however,  seems  to  be  more 
generally  active  than  hearing,  as  it  is  active  in  the  search 
and  selection  of  food. 

The  sense  of  Sight  among  the  Articulates  varies  from 
the  eye  speck,  scarcely  capable  of  perceiving  light,  to  elab¬ 
orate  systems  of  simple  and  compound  eyes,  as  in  the  heads 
of  insects,  while  such  as  the  Intestinal  Worms  are  wholly 
destitute  of  organs  of  vision.  Simple  eyes,  are  single  eyes 
placed  on  the  back  of  the  head,  in  numbers  from  one  to 
about  twenty ;  such  are  the  eyes  of  Spiders,  Lobsters  and 
the  young  or  larvae  of  insects ;  and  they  are  also  possessed, 
in  connection  with  compound  eyes,  by  many  insects. 

Compound  eyes  consist  of  a  pair  of  globes,  one  on  each 
side  of  the  head,  composed  on  the  surface  of  facets,  or 
lenses,  like  a  multiplying  glass,  varying  in  number  from 
about  fifty  to  ten  or  twenty  thousand  in  each  globe.  The 
internal  structure  of  these  shall  be  observed  in  connection 
with  the  study  of  insects. 

( )rgi ins  of  M oti <n i „ 

None  of  the  Articulates  are  possessed  of  an  endo - 
skeleton ,  and  many  of  them  are  destitute  of  even  a  shell 


ARTICULATES. - NATURAL  HISTORY. 


-75 


or  exo-skeleton.  The  Worms  and  the  larvrn,  or  young,  of 
all  the  higher  orders  are  wholly  devoid  of  anything  that 
may  be  called  a  shell  or  skeleton. 

The  exterior  skeleton  of  the  Lobster,  the  Crab,  and  the 
Insects  shall  be  taken  up  in  connection  with  a  study  of 
those  orders. 

Their  muscular  system  is  arranged  with  reference  to 
the  ring  division  of  the  body;  loose  among  the  Worms 
and  larvae,  or  young,  of  the  higher  classes,  but  extremely 
well  knit  and  powerful  among  the  insects. 

The  force  evinced  in  the  motions  of  a  Leetle,  or  a  Ilea, 
in  proportion  to  their  relative  sizes,  is  many  fold  greater 
than  that  of  the  human  frame,  or  the  ( )x  or  Horse. 

The  Natural  History  of  the  Articulates  is  the  most 
varied  and  interesting  of  the  entire  animal  kingdom. 

IS  ot  only  are  they  in  the  greatest  numbers  on  all  parts 
of  the  earth’s  surface — land,  air  and  water — but  their 
habits  and  appearances  also  furnish  the  greatest  variety. 

They  have  been  almost  coeval,  in  their  zoological  exist¬ 
ence,  with  the  Molusca  and  lladiata,  and  they  are  of  great 
importance  in  the  general  economy  of  life,  both  as  scaven¬ 
gers  of  the  land,  air  and  w^ater,  destroying  the  immense 
mass  of  decaying  material  that  otherwise  wTould  render 
these  regions  uninhabitable  for  the  higher  kinds  of  life  ; 
and  serve  also  as  food  for  myriads  of  animals  that  prey 
upon  them,  and,  indeed,  many  of  them  furnish  excellent 
and  abundant  food  for  Man  himself,  as  the  Crab,  Lobster, 
Shrimp,  and  even  numbers  of  the  insects  themselves. 

Their  uses  in  the  arts  and  in  medicine  are  also  very  ex¬ 
tensive  and  important. 


76  TYPE  OF  VERTEBRATES. - GENERATION - DIGESTION. 


CHAPTER  XXVIII. 


TYPE  OF  VERTEBRATES. 

This  type  takes  its  name  from  the  chief  bones  of  the  in¬ 
ternal,  or  endo-skeleton,  i.e.,  the  spinal  column  or  chain  of 
Vertebrae.  It  comprises  all  the  higher  animals — as 
Fishes,  Birds,  Reptiles,  and  Mammals — including  all  those 
that  are  intimately  connected  with  human  life  under  the 
term  of  domestic  animals,  and  of  all  the  highest — Man 
himself.  An  acquaintance  with  the  special  anatomy  of 
this  type  is  of  extreme  importance,  as  it  comprises  that  of 
the  human  frame ;  but,  as  we  are  not  especially  on  the 
study  of  anatomy  and  physiology,  we  shall  be  obliged  to 
confine  our  remarks,  in  this  important  department,  to  the 
barest  outline  that  will  answer  our  purposes. 

Generation  among  the  Vertebrates  is  sexual,  and  either 
oviparous  or  ovo-viviparous.  The  young,  in  many  orders, 
pass  through  marked  transformations  after  birth. 

Digestion. — The  organs  of  digestion  may  be  arranged 
under  three  divisions. 

1.  The  first,  that  hg  tvhich  the  food  is  prepared  for,  and 
conveyed  into  the  stomach.  This  is  chiefly  of  a  mechanical 
nature,  and  is  executed  by  the  organs  of  the  mouth  and 
the  oesophagus  or  gullet. 

The  mouth,  among  the  Fishes,  Reptiles,  and  Mammals, 
is  most  usually  armed  with  teeth,  but  among  the  Birds  we 
always  find,  instead  of  teeth,  a  hard,  horny  skin,  extend¬ 
ing  beyond  the  jaws,  forming  a  bill. 


TYPE  OP  VERTEBRATES. - DIGESTION. 


77 


The  teeth  of  Vertebrates  furnish  a  most  interesting 
range  of  variation,  by  which,  not  only  the  kind  of  food, 
but  the  character  and  habits  of  life  of  the  animals  may  be 
read. 

The  study  of  teeth  constitutes  the  science  of  Odontogra¬ 
phy .  A  tooth  consists  of  three  parts  or  materials,  as 
cementum  or  crusta-petrosa,  that  part  set  inside  of  the 
tooth  cavity  in  the  jaw ;  the  dentine,  the  softer  ivory, 
forming  the  greater  mass  of  the  upper  part ;  enamel, 
the  hard  limy  covering  of  the  upper  part  of  the  tooth. 
The  tongue  is  an  all-important  organ  in  the  work  of  seiz¬ 
ing,  preparing,  and  swallowing  the  food,  and  is  possessed 
of  a  wide  range  of  structure  and  activity. 

The  oesophagus  is  a  muscular  tube  leading  from  the 
mouth  to  the  stomach,  at  the  back  of  the  wind-pipe  or 
trachea.  It  is  widest  among  snakes  or  such  animals  as 
swallow  their  food  whole.  There  is,  perhaps,  no  act  of  the 
system  that  exhibits  a  more  perfect  specimen  of  animal 
mechanism  than  the  process  of  deglutition.  It  consists  of 
the  successive  action  of  a  series  of  muscles  that  effect  their 
end  in  the  most  complete  manner. 

2.  Those  that  have  been  exclusively  termed  the  proper 
digestive  organs ,  where  the  food  receives  its  appropriate 
chemical  change,  i.e.,  the  stomach,  a  bag  of  an  irregular 
oval  form,  occupying  the  upper  part  of  the  abdomen,  for 
the  solution  of  tne  food,  provided  with  as  much  or  more 
vitality  than  any  other  part  of  the  system,  and  hence  fur¬ 
nished  with  a  large  supply  of  blood  vessels  and  nerves ; 

3.  That  part  of  the  canal  that  removes  the  residue  of 
the  food,  after  the  nutritive  part  has  been  absorbed,  and 
a  part  of  the  waste  of  the  system — i.e.,  the  intestines. 


78 


TVPE  OE  VERTEBRATES. - RESPIRATION. 


Digestion  among  the  Vertebrates  is  essentially  of  three 
kinds : 

Herbiverous — plant  eating ; 

Carniverous — flesh  eating; 

Omniverous — eating  all  kinds  of  food  ; 

And  their  organs  are  constructed  with  special  reference  to 
their  different  methods  of  life. 

Respiration  among  the  Vertebrates  is  both  aerial  and 
aquatic.  A  large  proportion  of  the  lower  orders  of  the 
type,  as  all  the  Fishes  and  many  of  the  Rep  tiles,  breathe 
only  water ;  a  few  are  capable  of  both  aquatic  and  aerial 
respiration,  being  furnished  with  breathing  organs  appro¬ 
priate  for  both;  while  others,  as  the  Frogs,  breathe  fresh 
water  during  the  earlier  stages  of  their  existence,  and  only 
air  after  reaching  the  stages  of  maturity.  The  respiratory 
organs,  among  the  air-breathing  Vertebrates,  invariably 
take  the  form  of  lungs,  and  among  those  that  breathe 
water  the  form  of  gills,  or  branchiae. 


{ 


VERTEBRATES - CIRCULATION. 


79 


CHAPTER  XXIX. 


V  ERTEBRATES - CIRC  U  L  ATIOX . 


The  organs  of  circulation  among  the  Vertebrates  consist 
of  the : 

Heart. 

Arteries, 

Veins,  and 

Capillary  Vessels. 

These  organs,  though  ever  present  in  this  type,  are  in 
different  degrees  of  development  in  the  several  classes. 
This  variation  we  shall  speak  of  when  we  come  to  the 
study  of  the  classes,  for,  as  we  have  observed,  the  structure 
and  action  of  the  circulatory  organs  constitute  one  of  the 
principle  bases,  upon  which  the  modern  classification  of 
animals  is  founded.  At  present,  however,  we  will  take  a 
general  view  of  each  of  these  four  circulatory  organs : 

The  Heart ,  among  the  Vertebrates,  consists  of  two  por¬ 
tions — of  a  stronger  and  more  muscular  cavity,  called  a 
cent  ride,  for  propelling  the  blood  through  the  system,  or 
the  breathing  organs ;  and  a  weaker  and  less  muscular 
cavity,  called  an  auricle ,  for  receiving  the  blood  on  its  re¬ 
turn,  and  passing  it  back  into  the  ventricle,  again  to  be 
propelled  forward. 

Around  the  heart  is  a  tough  membranous  sac,  called  the 
Pericardium,  which  both  restrains  and  protects  it  in  its 
action.  Within  it  are  a  series  of  valves  that  prevent  the 
flowing  back  of  the  blood  from  its  course,  either  into  the 


80 


VERTEBRATES - CIRCULATION. 


arteries  and  veins  or  into  the  chambers  of  the  heart.  Such 
a  heart,  consisting  of  but  one  auricle  and  one  ventricle,  is 
called  a  single  heart,  and  is  found  among  all  the  Fishes, 
and  essentially,  also,  among  the  reptiles,  though  here 
(Beptilia)  the  heart  is  variously  modified,  and  brought  very 
near  to  the  double  heart  of  Birds  and  Mammals. 

Among  the  higher  or  warm-blooded  Vertebrates  (Birds 
and  Mammals),  the  heart  is  always  double,  and  possessed 
of  two  auricles  and  two  ventricles  ;  one  set  for  receiving 
and  sending  bach  the  blood  through  the  system,  and  the 
other  for  receiving  and  sending  it  through  the  lungs. 

The  Arteries  are  the  tubes  that  convey  the  blood  front 
the  heart,  and  distribute  it  throughout  the  body. 

The  ancients  first  called  these  tubes  “  arteries,”  because 
they  supposed  them  filled  with  a  vapor,  or  a  spirit,  as  they 
are  always  found  empty  after  death. 

In  the  complete  system  there  are  two  great  trunks,  one 
of  which  conveys  the  blood  through  the  system,  and  the 
other  through  the  breathing  organs. 

The  Veins  are  tubes,  that  gather  up  the  blood  from  all 
parts  of  the  system,  and  return  it  to  the  auricles  of  the 
heart ;  to  be  thence  again  sent  by  the  ventricles,  through 
the  arteries,  into  the  breathing  organs  to  all  parts  of  the 
body. 

The  capi/aries  form  the  intermediate  blood  channels  be¬ 
tween  the  finest  arteries  and  veins  When  looked  at 
under  the  microscope,  in  tbe  thin,  transparent  membrane 
of  an  animal — as  the  web  of  a  Frog’s  foot  or  the  thin  part 
of  a  Salamander’s  tail — they  are  found  to  be  of  different 


VERTEBRATES - CIRCULATION . 


81 


sizes,  some  conveying  two  or  more  rows,  and  others  only  a 
single  row  of  blood  corpuscles. 

The  same  tubes  are,  however,  found  at  different  times 
alternately  to  contract  and  d'diKO,  An  important  addition 
to  the  circulatory  system  of  Vertebrates,  not  found  among 
any  of  the  types  yet  spoken  of  (the  Invertebrates),  is  an 
entirely  new  system  of  vessels,  destined  to  absorb  from  the 
intestines  the  nutritious  products  of  the  digestive  process, 
and  convey  them  into  the  veins,  to  be  mixed  with  the  cir¬ 
culatory  blood.  These  are  called  Lymphatics  or  Lacteals. 

The  blood  of  all  the  Vertebrates  is  red,  and  is  composed 
of  microscopic  globules  of  variable  form  and  dimension  in 
different  animals. 

The  bile  among  the  Invertebrates,  that  are  possessed  of 
a  liver,  is  secreted  from  the  arterial  blood ;  but  among  the 
Vertebrates,  from  out  the  venous  blood.  And  hence  we  here 
find  another  new  system  of  vessels,  distinct  from  the  general 
circulation,  called  the  portal  system ;  in  connection  with 
which  we  also  find  another  remarkable  organ,  the  Spleen. 

The  peculiarities  of  cold  and  warm  blood  among  the 
Vertebrates  shall  be  taken  up  hereafter,  in  connection  with 
the  divisions  of  the  types. 


82 


VERTEBRATES - NERVOUS  SYSTEM. 


CHAPTER  XXX. 

VERTEBRATES - NERVOUS  SYSTEM. 

The  Nervous  System  of  the  Vertebrates  is  organized  on 
a  much  more  complex  and  elaborate  plan  than  that  of  any 
of  the  four  preceding  types. 

It  consists,  in  fact,  of  several  distinct  systems,  differently 
disposed  and  appropriated  to  different  offices. 

A  few  largely  developed  masses  of  nervous  matter,  or 
ganglia,  bound  together  by  tendonous  bands  and  mem¬ 
branes,  and  protected  by  a  bony  skull,  constitute  the  brain , 
which  presides  over  all  acts  of  voluntary  motion,  feeling 
and  sensation. 

From  the  brain  proceeds  a  long  chain  of  nervous 
centres,  or  ganglia,  joined  closely  together,  into  what 
is  called  the  Spinal  Cord ,  protected  by  a  chain  of 
bones  called  Vertebrae,  which  form,  with  arches,  along 
their  upper  or  back  surface  a  continuous  canal,  and  suc¬ 
cession  of  rings  from  the  head  to  the  end  of  the  trunk, 
and  among  many  into  the  tail,  if  one  exist. 

From  the  two  sides  of  the  Spinal  Cord,  between  the 
different  bones  of  the  Spinal  Column,  pass  out  pairs  of 
Nerves  ;  one  filament  being  the  Nerve  of  Motion,  and  the 
other  the  Nerve  of  Feeling  ;  and  these  distribute  them¬ 
selves,  by  successive  branchings,  to  the  voluntary  muscles 
and  integuments  of  the  two  sides  of  the  body. 


VERTEBRATES. - ORGANS  OF  SENSE 


83 


In  addition  to  the  above,  which  is  called  the  Cerebro¬ 
spinal  System ,  there  exists  in  the  Vertebrate  a  distinc- 
system  of  nervous  centres,  or  ganglia,  placed  amid  the 
organs  of  digestion,  respiration,  etc.,  and  connected  to¬ 
gether  by  another  set  of  branching  nerves,  called  the 
Sympathetic  System ,  which  presides  over  the  organic  life, 
or  involuntary  motions  of  the  animal,  as  those  of  circula¬ 
tion,  digestion,  respiration,  and  the  like. 

Five  Senses. 

The  Organs  of  Sense  are  developed  in  a  proportionate 
degree  with  the  nervous  system,  and  have  a  much  greater 
perfection  of  structure  and  regularity  of  arrangement  than 
in  any  of  the  Invertebrates. 

The  sense  of  Touch  among  the  Vertebrates  has  a  wide 
range  of  variation.  Among  the  higher  members  of  the 
type,  tactile  discrimination  is  exercised  more  or  less  from 
the  entire  surface  of  the  body,  but  is  always  keenest  in 
special  parts,  as,  in  the  human  system,  in  the  ends  of  the 
fingers  and  tongue,  the  lips,  the  palms  of  the  hands  and 
the  soles  of  the  feet ;  among  some  Monkeys,  even  at  the 
end  of  the  tail ;  among  the  Bats,  in  the  wings  ;  in  the  flesh¬ 
eating  quadrupeds,  in  the  whiskers  or  vibrissee ;  among  the 
Ant-eaters,  Moles,  Hogs  and  Elephants,  at  the  end  of  the 
nose.  Others,  again,  from  the  structure  of  their  covering, 
are  incapable  of  the  sense  over  their  entire  surface,  and 
can  exercise  it  only  through  particular  organs  or  parts. 

Of  such  are  the  Birds,  with  their  covering  of  feathers 
and  scales,  only  capable  in  any  degree  whatever  of  the 
sense  of  touch  in  their  toes  and  beak ;  the  Reptiles,  with 
their  slimy  or  scaly  covering,  feel  by  the  tongue,  and  per¬ 
haps  some  what  in  the  lips.  And  the  Fishes  have  the  same 


84 


VERTEBKATES - ORGANS  OF  SENSE. 


in  the  side  fins,  and  also,  sometimes,  in  projecting  feelers 
from  the  head,  called  Barbules.  In  all  cases,  however,  this 
sense  (tactile  discrimination)  is  due  to  exceedingly  delicate 
pimples,  called  Tactile  Papillae,  in  which  the  nerve  of 
sense  is  spread.  Wherever  these  papillae  are  arranged 
most  abundantly,  the  sense  is  keenest. 

The  Vertebrates  are  capable  of  enduring  the  widest 
range  of  climatic  temperature  existing  on  the  entire  surface 
of  the  globe,  and  in  the  remote  geological  ages  survived 
probably  yet  greater  extremes. 

Among  them  we  find  the  utmost  development  of  the 
muscular  sense,  both  in  accuracy  and  agility. 

Taste ,  among  the  Vertebrates,  is  developed  chiefly  in 
the  highest  type — that  of  Mammalia.  It  is  here  an  import¬ 
ant  guide  in  the  selection  of  food;  but  among  the  lower 
classes — Birds,  Peptiles,  and  Fishes — which  swallow  their 
food  whole,  it  scarcely,  if  at  all,  exists. 

The  sense  of  Smell ,  however,  is  more  widely  distributed 
throughout  the  type,  and  among  many  of  the  lower  Ver¬ 
tebrates  is  much  more  keenly  developed  than  in  the  human 
system. 

Hearing,  among  the  Vertebrates,  reaches  the  highest 
development.  The  Ear,  in  its  complete  condition,  as  in 
Man,  consists  of  three  portions :  the  external,  the  middle, 
and  the  internal  Ear. 

The  external  consists  of  the  outside  ear- trumpet,  and  the 
ear-tube  for  the  purpose  of  collecting  $nd  leading  the 
sound. 


VERTEBRATES. - ORGANS  OP  SENSE. 


85 


The  middle  ear  is  a  chamber  containing  a  tense  mem¬ 
brane,  called  the  ear-drum,  and  certain  bones,  for  the  pur¬ 
pose  of  collecting  and  conducting  the  vibrations  of  sound; 
and  the  internal  ear,  or  labyrinth,  in  which  are  spread  out, 
in  tubes  called  semi-circular  canals  and  cochlea,  or  shell, 
the  auditory  nerve,  or  nerve  of  hearing. 

All  these  parts,  in  their  complete  state,  are  found  by  no 
means  among  all  the  Vertebrates.  The  Fishes  have  but 
the  middle  ear,  and  from  these  we  find  all  degrees  of  vari¬ 
ation,  till  we  reach  the  complete  condition  in  Man,  and  the 
animals  associated  with  him  in  structure. 

Sight  is  attained  among  the  Vertebrates  by  eyes  con¬ 
structed  on  the  same  plan  as  in  the  human  system,  invari¬ 
ably  two  in  number,  lodged  in  cavities  formed  for  their  re¬ 
ception  in  the  bony  frame- work  of  the  face,  and  ex  1  libit 
in  the  simplicity  and  completeness  of  their  structure  a 
higher  plan  of  organization  than  any  we  have  yet  ex¬ 
amined. 

There  are  in  the  Vertebrate  eye  three  coats,  or  tunics  : 

1st.  Sclerotic  and  Cornea  ; 

2d.  Choroid,  Iris,  and  Ciliary  process; 

3d.  Retina  ; 

And  three  Lenses,  consisting  of  refracting  membranes  and 

humors : 

Aqueous  Humor, 

Crystaline  Lens, 

Vitreous  Humor. 


The  Sclerotic  is  the  outside  coat,  or  layer,  and  the  Cornea 
the  frontal  transparent  part  of  it.  The  Choroid  and  Oil - 


86 


VERTEBRATES. - ORGANS  OF  SENSE. 


iary  process  form  the  second  coat  or  membrane,  and  the 
Iris  the  front  curtain  of  the  eye,  the  centre  of  which  is  the 
pupil,  and  the  Retina  is  the  interior  colored  layer,  on 
which  the  optic  nerve  is  spread. 

■  * 

The  Aqueous  Humor  is  the  front  lens  of  the  eye,  it  is  a 
liquid,  filling  the  Cornea  above  and  below  the  Iris.  The 
Crystaline  Lens  is  a  beautiful  double  convex  lens,  of  a 
semi-solid  substance,  and  presents  some  of  the  most 
wonderful  mechanism  in  the  whole  animal  kingdom.  The 
Vitreous  Humor  is  the  inner  lens,  and  fills  the  globe  or 
body  of  the  eye  ;  it  is  formed  of  a  liquid  contained  in  bags, 
or  chambers,  formed  of  a  delicate  transparent  membrane. 

This  optical  instrument  is  adapted,  among  the  different 
Vertebrates,  to  the  various  kinds  of  life  they  lead ;  among 
the  Fishes,  for  aquatic  vision;  among  the  Birds,  for  a  teles¬ 
copic  range,  as  they  soar  aloft  in  the  sky,  or  microscopic 
distinctness  as  they  bring  their  eyes  within  a  few  inches  of 
their  prey,  in  seizing  it ;  and  in  the  human  system  for  the 
wide  and  wonderful  capabilities  of  the  eye  of  Man. 

It  is  protected  and  moved  by  systems  of  muscles,  glands 
and  protective  membranes,  and  hairs,  peculiar  to  the  vari¬ 
ous  necessities  of  life. 


Vertebrates — organs  of  motion. 


87 


CHAPTER  XXXI. 

VERTEBRATES - ORGANS  OF  MOTION. 

Vertebrate  motion  comprises  the  widest  range  and  most 
delicate  combination  of  mechanical  structures  that  can  be 
found  within  the  entire  realm  of  nature  or  art. 

All  Vertebrates  are  possessed  of  an  internal  or  enclo- 
skeleton ,  formed  of  bones,  arranged  on  the  same  model  or 
arche-type  plan. 

The  skeleton  answers  a  three-fold  purpose  : 

1.  It  forms  a  frame -work  to  give  shape  and  support  to 
the  body. 

2.  It  protects  the  more  delicate  organs  of  the  system  by 
a  series  of  cases  and  cages. 

3.  For  the  movements  of  the  body,  and  the  exertion  of 
force,  it  furnishes  a  system  of  levers,  joints,  hinges,  etc., 
constructed  on  the  most  complete  accordance  with  the  laws 
of  mechanics  and  motion. 

Bones  are  composed  chiefly  of  animal  cartilage  and 
phosphate  of  lime.  In  the  young  of  all  V ertebrates  and 
in  Fishes — especially  in  such  orders  as  the  Shark  and  Stur¬ 
geon — the  animal  cartilage  exists  in  greater  abundance.  In 
the  aged,  and  the  bones  of  Snakes  and  Birds,  exist  the 
greater  proportion  of  mineral  matter. 

Bones  are  constructed  of  delicate  plates  or  layers,  through 
which  traverse,  in  all  directions,  tubes  of  various  sizes, 


88 


VERTEBRATES - OROAKS  OE  MOTION. 


which  distribute  the  blood-vessels  and  nerves  which  give 
them  life  and  growth. 

These  tubes,  or  lacunae,  vary  to  a  considerable  extent  in 
form  and  size  in  the  several  classes  of  Vertebrates,  and  also 
among  the  orders,  in  several  cases,  so  that  by  examination 
of  them  under  the  microscope  the  tribe  to  which  the  bone 
belongs  may  be  determined. 

This  is  of  the  greatest  importance  in  the  study  of  the 
extinct  animals  of  past  geologic  ages. 

The  skeletons  of  Vertebrates  are  constructed  from  a 
model  or  archetype  plan,  consisting  of  a  succession  of 
bones,  called  vertebrae,  and  two  arches  with  a  pair  of  limbs 
on  each. 

This  model  plan  exists  within  no  one  animal,  as  in  each, 
those  parts  that  are  needed  for  the  special  kind  of  life 
the  animal  was  intended  to  lead,  are  the  most  developed. 
Many  parts  are  thus  in  one  order  of  Vertebrates  greatly 
enlarged,  and  in  others  are  rudimentary  or  altogether  want¬ 
ing  ;  while  in  another  order  of  Vertebrates,  these  same  parts 
may  exist  in  the  opposite  extreme  of  development.  For  ex¬ 
ample,  the  Snake,  to  accommodate  its  methods  of  locomo¬ 
tion,  has  an  entire  want  of  a  breast-bone,  while  the  Bird, 
for  the  same  purpose,  has  a  large,  strong,  keel-shaped 
breast-bone. 

The  Vertebrae  themselves,  are  made  of  model  or  elemen¬ 
tal  parts,  which  vary  greatly  in  their  size  and  development 
in  different  portions,  even  of  the  same  animal,  as  in  those 
of  the  head,  neck,  chest,  trunk,  and  tail. 

An  elemental  Vertebra — that  is,  one  in  which  all  the 


VERTEBRATES - ORGANS  OF  MOTION. 


89 


parts  are  equally  developed — would  be  constructed  as  fol¬ 
lows  : 


a.  Centre  or  body  of  the  bone. 

b.  Two  processes  called  the  nerve  or  Neural  processes, 
which  enclose  the  spinal  cord  or  the  great  nerve  masses 
forming  the  brain. 

('.  The  upper  or  Neural  Spine. 

(/.  The  two  transverse  or  side  processes. 

e .  The  two  lower  processes,  enclosing  the  chief  blood 
vessels,  and  called  the  Haemal  processes. 

f.  The  lower  or  Haemal  Spine. 

The  upper  arch  (g),  is  called  the  Neural  Arch,  and  the 
lower  arch  (A),  the  Haemal  Arch. 


90 


VERTEBRATES - ORGANS  OF  MOTION. 


The  archetype  or  model  skeleton  is  constructed  as  fol¬ 
lows  : 


Fig.  2. 


Metatarsus 
//  i  i  i  Phalanges 


VERTEBRATES - ORGANS  OE  MOTION. 


91 


EXPLANATION  OF  FIGURES  ON  MODEL  VERTEBRATE 
SKELETON. 

Chain  of  Vertebra ?. 

1.  Cranial  Vertebrae. 

2.  Cervical  Vertebrae. 

3.  Dorsal  Vertebrae. 

4.  Lumbar  Vertebrae. 

5.  Sacral  Vertebrae. 

6.  Coccygeal  or  Caudal  Vertebrae. 


Upper  Arch. 

1.  Clavicle. 

2.  Caiacoid. 

3.  Scapula. 


Lower  Arch. 

1.  Ilium. 

2.  Ischium. 

3.  Pubes. 


From  this  model  plan  there  has  been  no  deviation  since 
the  first  creation  of  Vertebrates  in  the  remote  ages  of  the 
past,  though  from  the  modifications  of  it,  have  been 
formed  the  great  number  of  shapes  that  appear  among 
Fishes,  Reptiles,  Birds  and  Mammals. 


92 


V ERTE BH A TES - MUSCULAR  SYSTEM. 


OH  AFTER  XXXII. 


VERTEBRATES - MUSCULAR  SYSTEM. 

Muscles,  among  all  animals,  are  the  direct  agents  or 
organs  of  motion. 

If  we  compare  the  bony  skeleton  of  the  animal  to  the 
masts,  yards  and  hulk  of  the  ship,  we  might  liken  the 
muscular  system  to  the  ropes  and  sails,  that  give  motion 
and  life  to  the  mass. 

Among  Vertebrates,  muscles  attain  their  most  complete 
condition  and  highest  development. 

A  muscle  consists  of  bundles  of  fibres,  bound  together 
by  a  silvery  sheath ;  and  by  the  alternate  contraction  and 
relaxation  of  this  bundle  of  little  threads  or  fibres  the 
motions  of  the  animal  are  attained. 

The  varied  arrangement  of  these  bundles  of  muscles,  on 
the  different  parts  of  the  body,  secure  the  symmetry  and 
beauty  of  form,  that  characterizes  most  members  of  this 
type,  especially  among  the  classes  of  Birds  and  Mammals. 

This  is  what  artists  term  Surface  or  Superficial  An¬ 
atomy. 

The  muscular  tissue  of  Vertebrates  presents  two  con¬ 
ditions — the  striped  and  the  unstriped.  All  the  muscles 
of  voluntary  motion,  together  with  those  of  the  heart,  are 
striped  and  of  a  red  color;  the  muscles  of  involuntary 
motion  are  unstriped  and  of  a  light  color. 


VERTEBRATES - MUSCULAR  SYSTEM . 


93 


The  muscles  of  an  animal  are  arranged  in  accordance 
with  the  special  structure  of  its  skeleton  ;  either  one  being 
given,  the  other  may  be  accurately  deduced  from  it.  Hence, 
by  the  discovery  of  bones  of  animals,  long  since  extinct, 
their  muscular  structure,  and  entire  form,  may  be,  and  in 
many  cases  has  been,  entirely  rebuilt  in  what  is  called  a 
Hestoration. 

The  individual  muscles  are  named  : 

1st.  From  their  situation. 

2d.  From  their  direction. 

3d.  From  their  uses. 

4th.  From  their  shape. 

5th.  From  the  number  of  their  divisions. 

6th.  From  their  points  of  attachment. 

All  Vertebrates  are  clothed,  or  cased,  in  an  integument, 
consisting  of  a  true  or  deep  skin,  called  the  Derma ,  in 
which  are  placed  the  surface  glands  and  the  nerves  of 
feeling ;  and  the  upper,  or  surface  layer,  called  the  Epi¬ 
dermis,  which  assumes,  in  the  several  orders,  a  very  wide 
range  of  variation,  such  as  the  delicate  skin  of  the  human 
system,  or  the  thick  hide  of  the  Elephant  or  Hippopota¬ 
mus,  or  is  developed  out  into  hair,  wool,  nails,  claws, 
hoofs,  scales,  horns,  feathers,  etc. 

The  Natural  History  of  Vertebrates  is,  of  all,  the  most 
important  and  intimately  connected  with  the  economy  of 
human  life,  as  it  includes  all  those  animals  that  are  daily 
associated  with  Man,  on  all  parts  of  the  earth,  where  he 
himself  resides ;  furnishing  him  food  of  their  flesh,  raiment 
of  their  covering,  and  sharing  with  him  his  toils,  privations 
and  dangers  ;  and,  furthermore,  indeed,  it  includes  the 


94 


VERTEBRATES - MUSCULAR  SYSTEM. 


history  of  Man  himself,  as  being  the  highest  member  of 
the  entire  animal  kingdom. 

The  geological  history  of  the  type  is  one  replete  with 
interest. 

Among  its  members  have  been  included  animals  of 
most  gigantic  size,  both  in  the  water  and  on  the  land ;  but 
a  consideration  of  these  points  must  be  reserved  for  a 
future  part  of  this  work. 

We  have  thus  reviewed  the  chief  structural  peculiarity 
of  the  five  types  of  the  Animal  Kingdom,  and  we  shall  next 
proceed  to  the  Methods  of  Study  of  the  Classes  of  Each 
Type. 

But  in  doing  this,  we  shall  not  trouble  the  learner  with 
a  full  review  of  all  their  structural  peculiarities,  but  merely 
make  a  brief  review  of  those  that  are  most  important  and 
characteristic. 


CLASSES  OF  ANIMALS - TABLE  OF  CLASSES. 


95 


OHAPTEE  XXXIII. 

CLASSES  OF  ANIMALS - TABLE  OF  CLASSES. 

Table  VI. 

'Sponges,  ok  Pobifeba, 
PEOTOZOA.  .  .  .  ^  Ehtzopods, 

Inftjsobia. 

'  Polyps, 

EADIATES.  .  .  J  Acalephs, 

Echinodebms. 
f  Acephala, 

MOLLUSKS.  .  .  .  <|  Gastebopods, 
i 

l_  Cephalopods. 

FWoBMS,  OB  VeBMES, 

AETICULATES  \  Cbtjstacea, 
1_Insectians. 

'Fishes, 


VEETEBEATES. 


Batbachians, 

Eeptiles, 

Bibds, 

Mammals. 


A  description  of  these  classes  will  be  given,  with  illus¬ 
trations,  in  Part  II. 


Ettd  ol  Jfart  l. 


H 


SCHOOL 

AND  • 

COLLEGE  LECTURES 


ON 


Anatomy  and  Physiology, 

ILLUSTRATED  WITH 

DRAWINGS 9  SPECIMENS, 

AND 

hvcioiflosooipies, 

WOULD  BE  GIVEN  TO 

EDUCATIONAL  INSTITUTIONS, 

BY 

ADRIAN  J.  EBELL,  Ph.B.,  M.D. 

Address  at 

PROFESSOR  FOX’S 

Collegiate  and  Engineering  Institute, 

ftoom  18  > 

4  COOPER  UNION  BUILDING, 

n 


NEW  VORK. 


POPULAR  LECTURES 

ON 


Illustrated  with  an  immense  collection  of 


Zoological,  Botanical,  Mineralogical,  Geolog¬ 
ical  and  Anatomical 
siREOinvnisnxrs, 

CASTS  AND  MODELS, 


jFrcc-Siaml  lUacliboat'd  fhauing, 

AND 

MAGNESIUM  LIGHT 

AND 

Hydro-Oxygen  Light  Screen  Microscopes, 

WOULD  BE  GIVEN  BEFOBE 

LYCEUMS, 

LECTURE, 

LIBRARY  AND 

CHRISTIAN  ASSOCIATIONS,  &c., 


ADRIAN  J.  EBELL,  PLB.,  M.D. 

For  particulars  address, 

DR.  EBELL, 

Room  is. 

Cooper  Union  Building , 

NEW  YORK. 


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